Apparatus and method for measurement in wireless communication system

ABSTRACT

A method of operating a user equipment (UE) in a wireless communication system, a method of operating an evolved Node B (eNB) in a wireless communication system, an apparatus of a UE in a wireless communication system, and an apparatus for operating an eNB in a wireless communication system are provided. The method of operating the UE includes receiving frequency measurement configuration information from an evolved Node B (eNB); performing frequency measurement in a radio resource control (RRC) idle mode or an RRC inactivate mode, based on the frequency measurement configuration information; and transmitting a result of the frequency measurement to the eNB.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application Nos. 10-2018-0035954 and 10-2018-0049250,filed on Mar. 28, 2018 and Apr. 27, 2018, respectively, in the KoreanIntellectual Property Office, the disclosures of which are incorporatedherein by reference in their entireties.

BACKGROUND 1. Field

The disclosure generally relates to a wireless communication system andmore particular to an apparatus and a method for measurement in awireless communication system.

2. Description of Related Art

In order to meet wireless data traffic demands, which have increasedsince the commercialization of the 4th-Generation (4G) communicationsystem, efforts to develop an improved 5th-Generation (5G) communicationsystem or a pre-5G communication system have been made. For this reason,the 5G communication system or the pre-5G communication system is calleda beyond-4G-network communication system or a post-LTE system.

In order to achieve a high data transmission rate, an implementation ofthe 5G communication system in a mmWave band (for example, 60 GHz band)is being considered. In the 5G communication system, technologies suchas beamforming, massive multiple-input multiple-output (MIMO), fulldimensional MIMO (FD-MIMO), array antenna, analog beam-forming, andlarge-scale antenna technologies are being discussed as means tomitigate a propagation path loss in the ultrahigh-frequency band andincrease a propagation transmission distance.

Further, technologies such as evolved small cell, advanced small cell,cloud radio access network (RAN), ultra-dense network, device-to-devicecommunication (D2D), wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (COMP), and receivedinterference cancellation have been developed in order to improve thesystem network in the 5G communication system.

In addition, the 5G system has developed advanced coding modulation(ACM) schemes such as hybrid frequency shift keying (FSK) and quadratureamplitude modulation (QAM) (FQAM) and sliding window superpositioncoding (SWSC), and has further developed advanced access technologiessuch as filter bank multi carrier (FBMC), non-orthogonal multiple access(NOMA), and sparse code multiple access (SCMA).

The 5G communication system operates to increase a signal gain through abeamforming scheme in order to overcome a path loss problem due tocharacteristics of a super-high frequency band (for example, mmWave). Inaddition, a user equipment (UE) is required to preliminarily performfrequency scanning to access an evolved Node B (eNB). As gain control isperformed for each beam in a beamforming communication system, a timespent for frequency scanning to access the eNB may increase.

SUMMARY

An aspect of the disclosure provides an apparatus and a method forfrequency measurement in a wireless communication.

Another aspect of the disclosure provides an apparatus and a method forrapidly performing frequency measurement in a wireless communicationsystem.

Another aspect of the disclosure provides an apparatus and a method forrapidly reporting a frequency measurement result in a wirelesscommunication system.

Another aspect of the disclosure provides an apparatus and a method forrapidly configuring carrier aggregation (CA) or dual connectivity (DC)in a wireless communication system.

Another aspect of the disclosure provides a definition of statuses of asecondary cell (SCell) in a wireless communication system.

Another aspect of the disclosure provides an apparatus and a method forswitching statuses of SCells in a wireless communication system.

Another aspect of the disclosure provides an apparatus and a method forperforming a frequency measurement operation based on statuses of SCellsin a wireless communication system.

Another aspect of the disclosure provides an apparatus and a method toefficiently configure CA or DC by performing frequency measurement at anearlier time point.

Another aspect of the disclosure provides to efficiently performmeasurement by defining states for SCells and performing measurementoperations according to the states.

In accordance with an aspect of the disclosure, a method of operating aUE in a wireless communication system is provided. The method includesreceiving frequency measurement configuration information from an eNB;performing frequency measurement in a radio resource control (RRC) idlemode or an RRC inactivate mode, based on the frequency measurementconfiguration information; and transmitting a result of the frequencymeasurement to the eNB.

In accordance with another aspect of the disclosure, a method ofoperating an eNB in a wireless communication system is provided. Themethod includes transmitting frequency measurement configurationinformation; receiving a result of a frequency measurement performed inan RRC idle mode or an RRC inactive mode, based on the frequencymeasurement configuration information, from a UE; and determiningwhether to perform CA or DC for the UE, based on the result of thefrequency measurement.

In accordance with another aspect of the disclosure, an apparatus of aUE in a wireless communication system is provided. The apparatusincludes at least one transceiver; and at least one processor connectedto the at least one transceiver, wherein the at least one processor isconfigured to receive frequency measurement configuration informationfrom an eNB, perform frequency measurement in an RRC idle mode or an RRCinactive mode, based on the frequency measurement configurationinformation, and transmit a result of the frequency measurement to theeNB.

In accordance with another aspect of the disclosure, an apparatus foroperating an eNB in a wireless communication system is provided. Theapparatus includes at least one transceiver; and at least one processorconnected to the at least one transceiver, wherein the at least oneprocessor is configured to transmit frequency measurement configurationinformation, receive a result of frequency measurement performed in anRRC idle mode or an RRC inactive mode, based on the frequencymeasurement configuration information, from a UE.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an illustration of a wireless communication system accordingto an embodiment;

FIG. 2 is a block diagram of a wireless protocol in a wirelesscommunication system according to an embodiment;

FIG. 3 is an illustration of a wireless communication system accordingto an embodiment;

FIG. 4 is an illustration of a wireless protocol of a wirelesscommunication system according to an embodiment;

FIG. 5 is a flowchart of a method for measuring frequencies andreporting the measurement by a UE in a wireless communication systemaccording to an embodiment;

FIG. 6 is a flowchart of a method for frequency measurement and ameasurement report by an eNB in a wireless communication systemaccording to an embodiment;

FIG. 7 is a flow diagram of signaling between an eNB and a UE forfrequency measurement and a measurement report in a wirelesscommunication system according to an embodiment;

FIG. 8 is a flow diagram of signaling between an eNB and a UE for afrequency measurement and a measurement report in a wirelesscommunication system according to an embodiment;

FIG. 9 is a flowchart of a method for configuring an SCell by a UE in awireless communication system according to an embodiment;

FIG. 10 is a flow diagram of signaling between an eNB and a UE forconfiguring an SCell in a wireless communication system according to anembodiment;

FIG. 11 is an illustration of state transition of an SCell according toan embodiment;

FIG. 12A is an illustration of medium access control (MAC) controlinformation supporting the state transition for an SCell in a wirelesscommunication system according to an embodiment;

FIG. 12B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 13A is an illustration of MAC control information supporting thestate transition for an SCell in a wireless communication systemaccording to an embodiment;

FIG. 13B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 13C is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 14A is an illustration of MAC control information supporting thestate transition for an SCell in a wireless communication systemaccording to an embodiment;

FIG. 14B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 15A is an illustration of MAC control information supporting thestate transition for an SCell in a wireless communication systemaccording to an embodiment;

FIG. 15B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 16A is an illustration of MAC control information supporting thestate transition for an SCell in a wireless communication systemaccording to an embodiment;

FIG. 16B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 17A is an illustration of MAC control information supporting thestate transition for an SCell in a wireless communication systemaccording to an embodiment;

FIG. 17B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 18A is an illustration of MAC control information supporting thestate transition for an SCell in a wireless communication systemaccording to an embodiment;

FIG. 18B is an illustration of an octet structure according to MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment;

FIG. 19 is a block diagram of an eNB in a wireless communication systemaccording to an embodiment; and

FIG. 20 is a block diagram of a UE in a wireless communication systemaccording to an embodiment.

DETAILED DESCRIPTION

The terms used in the disclosure are only used to describe certainembodiments, but are not intended to limit the disclosure. A singularexpression may include a plural expression unless they are definitelydifferent in a context. Unless defined otherwise, all terms used hereinhave the same meanings as those commonly understood by a person skilledin the art to which the disclosure pertains. Such terms as those definedin a generally used dictionary may be interpreted to have the meaningsequal to the contextual meanings in the relevant field of art, but arenot intended to be interpreted to have ideal or excessively formalmeanings unless clearly defined in the disclosure. In some cases, eventhe terms defined in the disclosure are not intended to be interpretedto exclude embodiments of the disclosure.

Hereinafter, various embodiments of the disclosure are described basedon an approach of hardware. However, various embodiments of thedisclosure include a technology that uses both hardware and software andthus, the various embodiments of the disclosure may not exclude theperspective of software.

Hereinafter, the disclosure relates to a method and an apparatus inwhich a UE in an RRC idle mode or an RRC inactive mode performsfrequency measurement and rapidly reports a frequency measurement resultto an eNB, and the eNB rapidly configures CA technology in a wirelesscommunication system. The RRC idle mode may be referred to as an RRCidle state (RRC inactive state), and the RRC inactive mode may bereferred to as an RRC inactive state.

In order to support a service having a high data transmission rate and alow transmission delay in a wireless communication, an eNB is requiredto rapidly configure CA or DC technology in a UE. However, a frequencymeasurement result of a UE is needed to configure the technology in theUE. Accordingly, in the disclosure, a UE performs, in advance, frequencymeasurement in an RRC idle mode or an RRC inactive mode as well as anRRC-connected mode and rapidly reports a frequency measurement result toan eNB, and, thus, the eNB is required to rapidly configure frequency CAtechnology.

The disclosure discloses a method by which, when a UE transitions froman RRC-connected mode to an RRC idle mode or an RRC inactive mode, aneNB configures frequency measurement configuration information(intra-inter frequency measurement configuration) through an RRC messageor broadcasts the frequency measurement configuration informationthrough system information of each cell in order to allow the UE toperform frequency measurement in advance in the RRC idle mode or the RRCinactive mode in a wireless communication system. When the UE determinesa valid frequency measurement result among measured frequencymeasurement results and indicates that there is a valid frequencymeasurement result to the eNB, the eNB may make a request for thefrequency measurement result to the UE as necessary and, thus, the UEmay report the frequency measurement result. Accordingly, the eNB mayconfigure the UE to perform frequency measurement in the RRC idle modeor the RRC inactive mode before the UE configures a connection to anetwork. The eNB may receive the frequency measurement result. The eNBmay rapidly configure CA if necessary. As described above, the eNB mayrapidly provide a greater amount of data to the UE through smallsignaling overhead and a low transmission delay.

Hereinafter, the operating principle of the disclosure is described indetail with reference to the accompanying drawings. In describing thedisclosure below, a detailed description of related known configurationsor functions incorporated herein will be omitted when it is determinedthat the detailed description thereof may unnecessarily obscure thesubject matter of the disclosure. The terms which are described beloware terms defined in consideration of the functions in the disclosure,and may be different according to users, intentions of the users, orcustoms. Therefore, the definitions of the terms should be made based onthe contents throughout the disclosure.

In describing the disclosure below, a detailed description of relatedknown configurations or functions incorporated herein are omitted whenthe detailed description thereof may unnecessarily obscure the subjectmatter of the disclosure. Hereinafter, embodiments of the disclosure aredescribed with reference to the accompanying drawings.

In the following description, terms for identifying an access node,referring to network entities, referring to messages, referring tointerfaces between network entities, and referring to various pieces ofidentification information are used for convenience of description.Therefore, the disclosure is not intended to be limited by the termsprovided below, and other terms that indicate subjects having equivalentmeanings may be used.

The disclosure uses terms and names defined in a 3rd GenerationPartnership Project Long Term Evolution (3GPP LTE) standard. However,the disclosure is not intended to be limited to the terms and names butmay be equally applied to a system according to another standard. In thedisclosure, an eNB is interchangeable with a generation Node B (gNB).That is, a base station described as an eNB may indicate a gNB.

FIG. 1 is an illustration of a wireless communication system accordingto an embodiment. The wireless communication system may be a system (forexample, an evolved packet system (EPS)) to which long term evolution(LTE) radio access technology (RAT) is applied. Hereinafter, the systemto which LTE RAT is applied may be called an “LTE system”.

Referring to FIG. 1, a RAN of the LTE system includes an eNBs 105, 110,115, and 120, a mobility management entity (MME) 125, and a servinggateway (S-GW) 130. A UE 135 may access an external network through theeNBs 105, 110, 115, or 120 and the S-GW 130.

The eNBs 105, 110, 115, and 120 correspond to conventional node Bs of auniversal mobile telecommunication system (UMTS). The eNBs 105, 110,115, or 120 may be connected to the UE 135 through a wireless channeland may play more complex roles than a conventional node B. In the LTEsystem, since all user traffic including a real-time service such asvoice over Internet protocol (VoIP) through an Internet protocol isserved through a shared channel, a device for collecting and schedulingstatus information such as buffer statuses, available transmission powerstatuses, and channel statuses of UEs is required, and the eNBs 105,110, 115, and 120 serve as this device. One eNB may generally control aplurality of cells. For example, in order to implement a transmissionrate of 100 megabits per second (Mbps), the LTE system uses anorthogonal frequency division multiplexing (OFDM) as a radio accesstechnology in a bandwidth of 20 MHz. Further, a modulation scheme and anadaptive modulation and coding (AMC) scheme of determining a channelcoding rate are applied to the LTE system in accordance with the channelstatus of the UE. The S-GW 130 is a device for providing a data bearer.The S-GW 130 may generate or remove a data bearer according to a controlof the MME 125. The MME 125 is a device for performing a function ofmanaging mobility of the UE and various control functions, and may beconnected to a plurality of eNBs.

FIG. 2 is a block diagram of a wireless protocol in a wirelesscommunication system according to an embodiment. The protocol structuremay be a protocol structure in the LTE system.

Referring to FIG. 2, in the LTE system, a wireless protocol of a UE 135may include a packet data convergence protocol (PDCP) 205, radio linkcontrol (RLC) 210, MAC 215, and physical layer (PHY) 220. In the LTEsystem, a wireless protocol of an eNB 105 may include a PDCP 240, RLC235, MAC 230, and PHY 225.

The PDCP 205 and the PDCP 240 may compress or decompress an IP header.The PDCP 205 and PDCP 240 may compress or decompress the IP headerthrough a robust header compression (ROHC) scheme. Main functions of thePDCP are described below and the PDCP 205 or the PDCP 240 may perform atleast one of the following functions.

-   -   Header compression and decompression function (header        compression and decompression: ROHC only)    -   User data transmission function (transfer of user data)    -   Sequential delivery function (in-sequence delivery of upper        layer packet data units (PDUs) at PDCP re-establishment        procedure for RLC acknowledge mode (AM))    -   Reordering function (for split bearers in DC (only support for        RLC AM): PDCP PDU routing for transmission and PDCP PDU        reordering for reception)    -   Duplicate detection function (duplicate detection of lower layer        service data units (SDUs) at PDCP re-establishment procedure for        RLC AM)    -   Retransmission function (retransmission of PDCP SDUs at handover        and, for split bearers in DC, of PDCP PDUs at PDCP data-recovery        procedure, for RLC AM)    -   Ciphering and deciphering function (ciphering and deciphering)    -   Timer-based SDU deletion function (timer-based SDU discard in        uplink)

The RLC 210 or the RLC 235 may reconfigure the PDCP PDU to be a propersize and perform an automatic repeat request (ARQ) function. Mainfunctions of the RLC 210 and the RLC 235 are described below and the RLC210 or the RLC 235 may perform at least one of the following functions.

-   -   Data transmission function (transfer of upper layer PDUs)    -   ARQ function (error correction through ARQ (only for AM data        transfer))    -   Concatenation, segmentation, and reassembly function        (concatenation, segmentation and reassembly of RLC SDUs (only        for unacknowledgement mode (UM) and AM data transfer))    -   Re-segmentation function (re-segmentation of RLC data PDUs (only        for AM data transfer))    -   Reordering function (reordering of RLC data PDUs (only for UM        and AM data transfer)    -   Duplication detection function (duplicate detection (only for UM        and AM data transfer))    -   Error detection function (protocol error detection (only for AM        data transfer))    -   RLC SDU deletion function (RLC SDU discard (only for UM and AM        data transfer))    -   RLC re-establishment function (RLC re-establishment)

The MAC 215 or the MAC 230 may be connected to a plurality of RLC layerdevices included in the UE. The MAC 2115 or the MAC 230 may multiplexRLC PDUs to the MAC PDU. The MAC 2115 or the MAC 230 may demultiplex RLCPDUs from the MAC PDU. Main functions of the MAC 215 or the MAC 230 aredescribed below and may perform at least one of the following functions.

-   -   Mapping function (mapping between logical channels and transport        channels)    -   Multiplexing and demultiplexing function        (multiplexing/demultiplexing of MAC SDUs belonging to one or        different logical channels into/from transport blocks (TBs)        delivered to/from the physical layer on transport channels)    -   Scheduling information report function (scheduling information        reporting)    -   Hybrid ARQ (HARQ) function (error correction through HARQ)    -   Logical channel priority control function (priority handling        between logical channels of one UE)    -   UE priority control function (priority handling between UEs by        means of dynamic scheduling)    -   Multimedia broadcast multicast service (MBMS) service        identification function (MBMS service identification)    -   Transport format selection function (transport format selection)    -   Padding function (padding)

The PHY 220 or the PHY 225 may perform channel-coding and modulation onhigher layer data to generate a symbol (for example, an OFDM symbol) andtransmit the generated symbol through a wireless channel. The PHY 220 orthe PHY 225 may perform demodulation and channel-decoding on the symbolreceived through the wireless channel and transmit the symbol to ahigher layer.

FIG. 3 is an illustration of a wireless communication system accordingto an embodiment. The wireless communication system may support a RATdifferent from LTE of FIG. 1. The wireless communication system mayinclude a system to which a new radio (NR) RAT is applied. Hereinafter,in the disclosure, a system to which the NR RAT is applied may be calledan “NR system”, a “5G communication system”, or a “next-generationmobile communication system”. According to an embodiment of thedisclosure, the NR RAT may be an RAT which achieves a higher datatransmission rate, higher reliability, and/or lower-latency datacommunication compared the LTE RAT.

Referring to FIG. 3, a RAN of the NR system includes the eNBs 105, 110,115, and 120, the MME 125, and the S-GW 130. The UE 135 may access anexternal network through the eNBs 105, 110, 115, or 120 and the S-GW130.

A radio access network of the NR system may include an NRnext-generation Node B (NR gNB) 310 (hereinafter, referred to as a gNB)and an NR core network (NR CN) 305. The NR gNB may be called anext-generation eNB, an NR eNB, or a gNB. The UE 315 of the NR system(hereinafter, referred to as an NR UE or a terminal) may access anexternal network through the NR gNB 310 and the NR CN 305.

The NR gNB 310 corresponds to an eNB of the conventional LTE system. TheNR gNB may be connected to the NR UE 315 through a radio channel and mayprovide better service than the conventional node B. Since all usertraffic is served through a shared channel in the next-generation mobilecommunication system, the NR gNB 310 may collect and schedule statusinformation such as buffer statuses, available transmission powerstatuses, and channel statuses of UEs. The NR gNB 310 generally controlsa plurality of cells. The NR system may support the conventional maximumbandwidth or wider in order to implement a super-high data transmissioncompared to the current LTE system and a beamforming technology may beadditionally grafted thereon through the RAT as an OFDM scheme. Further,a modulation scheme and an AMC scheme of determining a channel codingrate are applied in accordance with a channel status of the UE. The NRCN 305 may perform a function of supporting mobility, establishing abearer, and configuring quality of service (QoS). The NR CN 305 is adevice for performing a function of managing mobility of the UE andvarious control functions and may be connected to a plurality of eNBs.The NR system may interwork with the conventional LTE system. Forexample, the NR CN 305 is connected to the MME 325 through a networkinterface. The MME 325 may be connected to an eNB 330 which is theconventional eNB.

FIG. 4 is an illustration of a wireless protocol of a wirelesscommunication system according to an embodiment. The structure of thewireless protocol may be a structure of a wireless protocol of the NRsystem.

Referring to FIG. 4, a wireless protocol of the UE of the NR system mayinclude an NR PDCP 405, an NR RLC 410, an NR MAC 415, and an NR PHY 420.A wireless protocol of the NR gNB of the NR system may include an NRPDCP 445, an NR RLC 435, an NR MAC 430, and an NR PHY 425.

The NR PDCP 405 and the NR PDCP 440 may perform at least one of thefollowing functions.

-   -   Header compression and decompression function (header        compression and decompression: ROHC only)    -   User data transmission function (transfer of user data)    -   Sequential delivery function (in-sequence delivery of upper        layer PDUs)    -   Non-sequential delivery function (out-of-sequence delivery of        upper layer PDUs)    -   Reordering function (PDCP PDU reordering for reception)    -   Duplicate detection function (duplicate detection of lower layer        SDUs)    -   Retransmission function (retransmission of PDCP SDUs)    -   Ciphering and deciphering function (ciphering and deciphering)    -   Timer-based SDU deletion function (timer-based SDU discard in        uplink)

In the above examples, the recording function of the NR PDCP is afunction of sequentially reordering PDCP PDUs received by a lower layerbased on a PDCP sequence number (SN). The reordering function mayinclude at least one of a function of sequentially transmittingreordered data to a higher layer, a function of transmitting the dataregardless of sequences thereof, a function of recording PDCP PDUs whichare lost due to the reordering, a function of reporting statuses of thelost PDCP PDUs to a transmitting side, and a function of making arequest for retransmitting the lost PDCP PDUs.

The NR RLC 410 and the NR RLC 435 may perform at least one of thefollowing functions.

-   -   Data transmission function (transfer of upper layer PDUs)    -   Sequential delivery function (in-sequence delivery of upper        layer PDUs)    -   Non-sequential delivery function (out-of-sequence delivery of        upper layer PDUs)    -   ARQ function (error correction through ARQ)    -   Concatenation, segmentation, and reassembly function        (concatenation, segmentation and reassembly of RLC SDUs)    -   Re-segmentation function (re-segmentation of RLC data PDUs)    -   Reordering function (reordering of RLC data PDUs)    -   Duplicate detection function (duplicate detection)    -   Error detection function (protocol error detection)    -   RLC SDU deletion function (RLC SDU discard)    -   RLC re-establishment function (RLC re-establishment)

In the above examples, the sequential delivery function (in-sequencedelivery) of the NR RLC is a function of sequentially transmitting RLCSDUs received from a lower layer to the higher layer. The sequentialdelivery function may include, when one original RLC SDU is divided intoa plurality of RLC SDUs and received, a function of reassembling andtransmitting the RLC SDUs, a function of reordering the received RLCPDUs based on an RLC SN or a PDCP SN, a function of recording RLC PDUslost due to the reordering, a function of reporting statuses of the lostRLC PDUs to a transmitting side, a function of making a request forretransmitting the lost RLC PDUs, a function of, when there is a lostRLC SDU, sequentially transmitting only RLC SDUs to a higher layerbefore the lost RCL SDU, a function of, when a predetermined timerexpires although there is a lost RLC SDU, sequentially transmitting allRLC SDUs received before the timer starts to a higher layer, and afunction of, when a predetermined timer expires although there is a lostRLC SDU, sequentially transmitting all RLC SDUs received to a higherlayer. Further, the NR RLC may sequentially (that is, according to anSN, regardless of an SN, or in an order of arrival) process RLC PDUs anddeliver the RLC PDUs to the PDCP regardless of sequences thereof (out-ofsequence delivery), or when segments are received, may receive segmentsstored in a buffer or to be received in the future to reconfigure onecomplete RLC PDU and then transmit the RLC PDU to the PDCP to processthe reconfigured RLC PDU. The NR RLC layer may not include aconcatenation function. The function may be performed by the NR MAClayer or may be replaced with a multiplexing function of the NR MAClayer.

In the above examples, the non-sequential delivery function(out-of-sequence delivery) of the NR RLC is a function of transmittingRLC SDUs received from a lower layer to a higher layer regardless ofsequences thereof. The non-sequential delivery function may include,when one original RLC SDU is divided into a plurality of RLC SDUs andreceived, a function of reassembling and transmitting the RLC SDUs and afunction of storing RLC SNs or PDCP SNs of the received RCL PDUs,reordering the RLC PDUs, and recording lost RLC PDUs.

The NR MAC 415 or the NR MAC 430 may be connected to a plurality of NRRLC layer devices included in one UE. The NR MAC 415 or the NR MAC 430may perform at least one of the following functions.

-   -   Mapping function (mapping between logical channels and transport        channels)    -   Multiplexing and demultiplexing function        (multiplexing/demultiplexing of MAC SDUs)    -   Scheduling information report function (scheduling information        reporting)    -   HARQ function (error correction through HARQ)    -   Logical channel priority control function (priority handling        between logical channels of one UE)    -   UE priority control function (priority handling between UEs by        means of dynamic scheduling)    -   MBMS service identification function (MBMS service        identification)    -   Transport format selection function (transport format selection)    -   Padding function (padding)

The NR PHY 420 or the NR PHY 425 may generate a symbol (for example, anOFDM symbol) by performing channel-coding and modulation on higher layerdata, and transmit the generated symbol through a wireless channel. TheNR PHY 420 or the NR PHY 425 may perform demodulation andchannel-decoding on the symbol received through the wireless channel andtransmit the symbol to a higher layer.

Hereinafter, the operation of the eNB or the UE in the wirelesscommunication system according to the disclosure is described. A basestation (BS) may be referred to as an access point (AP), an eNB, a 5Gnode, a next-generation NodeB (G NodeB or gNB), a wireless point”, orother terms having equivalent meaning. According to an embodiment, theeNB may be connected to one or more transmission/reception points(TRPs). The eNB may transmit a downlink signal to the UE or receive anuplink signal through one or more TRPs. Hereinafter, a network node fortransmitting a wireless signal to the UE is described as an example ofthe eNB in the disclosure. However, the disclosure is not intended to belimited thereto. Transmission of the wireless signal may include aconfiguration in which the eNB is connected to the TRP and the TRPtransmits the wireless signal.

A terminal may be referred to as a UE, an NR UE, a mobile station, asubscriber station, a customer premises equipment (CPE), a remoteterminal, a wireless terminal, an electronic device, a user device, orother terms having the equivalent meaning.

In the LTE system or the NR system (next-generation mobile communicationsystem), the UE may perform frequency measurement while performing acell reselection procedure in order to find a serving cell or a cell onwhich the UE camps in an RRC idle mode or an RRC inactive mode. However,the UE may separately measure a plurality of frequencies or may notreport the frequency measurement result to the network. The UE mayperform frequency measurement based on frequency measurementconfiguration information configured by the network after configuringthe connection to the network and transitioning to the RRC-connectedmode, and if a preset condition is satisfied, report the measurementresult to the eNB.

That is, the eNB may configure the UE according to frequency measurementconfiguration information. The eNB may configure, in the UE, frequencies(for example, a frequency list) or frequency bands to be measured, put apriority for each frequency and configure the order of measurement,configure a filtering method of frequency intensity (for example, L1filtering, L2 filtering, and L3 filtering methods, or a coefficient anda calculation method used for measurement), and configure an event or acondition for measurement in frequency measurement, a reference formeasurement compared to the current serving cell (or a frequency onwhich the UE currently camps), an event or a condition under which themeasured frequency result is reported, a reference or a condition underwhich a frequency is reported compared to the current serving cell (or afrequency on which the UE currently camps), and a period on which thefrequency measurement result is reported. The UE measures correspondingfrequencies according to the frequency configuration made by the eNB andreports frequency measurement results to the eNB according to acorresponding event or condition. The eNB may determine whether to applyCA or DC to the UE based on the frequency measurement results receivedfrom the UE.

The UE according to an embodiment of the disclosure may performfrequency measurement in the RRC idle mode or the RRC inactive mode. TheeNB may set frequency measurement configuration in the UE throughsignaling (for example, an RRC message or system information). Further,the eNB may allow the UE to rapidly report the measured frequencymeasurement result, and when the eNB determines that the application ofCA or DC is required, rapidly configure and activate CA or DC based onthe frequency measurement result and allow the UE to use the CA or DC.

The disclosure discloses allowing the UE to start frequency measurementbefore transition to the RRC-connected mode and to rapidly report themeasurement result before or after entering the RRC-connected mode. Theproposed technologies may be very useful when the network rapidlyconfigures CA or DC in the UE in an environment in which small cells aredeployed in a macro cell.

FIG. 5 is a flowchart of a method for measuring frequencies andreporting the measurement by a UE in a wireless communication systemaccording to an embodiment. For example, operations in which the UE inan RRC idle mode or an RRC inactive mode performs early frequencymeasurement and rapidly reports the frequency measurement result (fastmeasurement report) in the NR system of the disclosure is describedbelow with reference to FIG. 5. The UE corresponds to the UE 135 of FIG.1 or the UE 315 of FIG. 3.

Referring to FIG. 5, in step 501, the UE may receive frequencymeasurement configuration information. The frequency measurementconfiguration information may include parameters required when the UEperforms frequency measurement. For example, the frequency measurementconfiguration information may include channel information to bemeasured, a measurement period, and a condition for reporting themeasurement result. According to an embodiment, the frequencymeasurement configuration information may be information for configuringparameters required when the UE in the RRC idle mode or the RRC inactivemode performs frequency measurement.

The frequency measurement configuration information may be transmittedby the eNB through various schemes. For example, the frequencymeasurement configuration information may be transmitted while beingincluded in an RRC message. For example, the RRC message may be an RRCmessage for making the UE transition from the RRC-connected mode to theRRC idle mode or the RRC inactive mode. For example, the RRC message maybe a message transmitted from the eNB to the UE when the UE establishesthe RRC connection with the eNB. For example, the frequency measurementconfiguration information may be transmitted while being included insystem information. For example, the frequency measurement configurationinformation may be transmitted from the eNB to the UE in cellreselection in the RRC idle mode. Transmission of the frequencymeasurement configuration information is described below with referenceto FIGS. 7 and 8.

In step 503, the UE may perform frequency measurement. The UE mayperform frequency measurement in the RRC idle mode or the RRC inactivemode as well as the RRC-connected mode. The UE may more rapidly acquirethe frequency measurement result by performing the frequency measurementearlier in the RRC idle mode or the RRC inactive mode. According to anembodiment, the frequency measurement may be performed before randomaccess. The frequency measurement may be performed beforereconfiguration of the RRC connection.

The frequency measurement in the RRC idle mode or the RRC inactive modemay be different from frequency measurement in the RRC-connected mode.For example, a signal to be measured in the RRC idle mode or the RRCinactive mode and a channel quality parameter (for example, receivedsignal strength indicator (RSSI)) of the corresponding signal may bedifferent from a signal to be measured in the RRC-connected mode and achannel quality parameter (for example, reference signal received power(RSRP)) of the corresponding signal.

According to an embodiment, a time point at which the frequencymeasurement is initiated may be variously determined. For example, theUE may initiate the frequency measurement at a time point at whichfrequency measurement configuration information of step 501 is received.For example, the UE may initiate frequency measurement after apredetermined interval from the time point at which the frequencymeasurement configuration information of step 501 is received. A timepoint at which the frequency measurement ends may be variouslydetermined. For example, when the result of the frequency measurement isreported, the frequency measurement may end. For example, when ameasurement interval arrives, the frequency measurement may end.Embodiments related to the time point and the end of the frequencymeasurement are described below in greater detail with reference toFIGS. 7 and 8.

In step 505, the UE may report the measurement result. The UE maytransmit the frequency measurement result of step 503 to the eNB.Signaling of the report of the measurement result of the UE may bedefined in various ways. In an embodiment, the UE may inform the eNB ofthe existence of the measurement result. The eNB makes a request for themeasurement result to the UE if necessary. Upon receiving the requestfrom the eNB, the UE may report the measurement result to the eNB. TheeNB may make a request for the measurement result to the UE. The UE mayreport the measurement result to the eNB in response to the request fromthe eNB. The UE may report the measurement result to the eNB eventhrough there is no request from the eNB. For example, the UE mayperiodically report the measurement result. For example, the UE mayreport the measurement result when a particular condition is satisfied.

According to, the UE may report at least a portion of the measurementresult to the eNB rather than reporting all of the measurement result tothe eNB. For example, the UE may transmit the frequency measurementresult for SCells which satisfy a predetermined condition to the eNB.Examples of the condition are described below in greater detail withreference to FIGS. 7 and 8.

According to an embodiment, the UE may report the measurement result tothe eNB in various manners. The UE may report the measurement resultthrough a random access procedure, or RRC message or RRC reconfigurationmessage for the RRC connection. Examples of the transmission scheme ofthe measurement result is described below in greater detail withreference to FIGS. 7 and 8.

Additionally, in an embodiment, the UE may receive configurationinformation from the eNB. The configuration information may includeparameters for configuration for supporting a particular communicationtechnology, for example, configuration for CA or DC in the UE. The eNBmay determine whether to perform CA or DC with the UE based on themeasurement result received from the UE. When the eNB desires toconfigure CA or DC, the eNB may transmit the configuration informationto the UE. For example, the eNB may transmit configuration informationfor configuring or adding the SCell for CA. The eNB may determine theSCell based on the reported measurement result. For example, the eNB maytransmit configuration information for configuring a secondary cellgroup (SCG) for DC.

The UE may terminate the frequency measurement according to anembodiment. When the frequency measurement performed in the RRC inactivemode or the RRC idle mode is completed, the UE may stop the frequencymeasurement. Further, the UE may stop the frequency measurement whilereporting the measurement result like in step 505. In addition, the UEmay stop the frequency measurement if a predetermined condition issatisfied.

FIG. 6 is a flowchart of a method for frequency measurement and ameasurement report by the eNB in a wireless communication systemaccording to an embodiment. The eNB corresponds to the eNB 110 of FIG.1, the gNB 310, or the eNB 315 of FIG. 3.

Referring to FIG. 6, the eNB may transmit frequency measurementconfiguration information in step 601. The frequency measurementconfiguration information may include parameters required for frequencymeasurement in the RRC idle mode or the RRC inactive mode of the UE. TheeNB may transmit frequency measurement configuration information throughthe RRC message or by broadcasting system information, or may reuse thepreviously used frequency measurement configuration information. The eNBmay transmit frequency measurement configuration information for the RRCidle mode or the RRC inactive mode to the UE in the RRC-connected mode.The eNB may transmit frequency measurement configuration information tothe UE in the RRC idle mode or the RRC inactive mode before receiving arandom access preamble. The UE may transmit frequency measurementconfiguration information to the UE before establishing the connectionagain in the RRC inactive mode.

In step 603, the eNB may receive the measurement result from the UE. TheUE may perform measurement based on the frequency measurementconfiguration information of step 601. The UE transmits the measurementresult to the eNB according to various signaling methods. The UE maytransmit the measurement result to the eNB according to a predeterminedevent or in every measurement. The UE may transmit the measurementresult according to a request from the eNB. The eNB may make a requestfor the measurement result when a predetermined condition is satisfied(or a particular event is generated). The UE may transmit a signalinforming that there is a valid measurement result to the eNB, and theeNB receiving the signal may make a request for the valid measurementresult. Accordingly, the eNB may receive the measurement result.

The measurement result may include measurement results for SCells. TheUE may perform measurement for the SCells according to the frequencymeasurement configuration information. The measurement results for theSCells include measurement results acquired based on a status of each ofthe SCells (for example, an activated, deactivated, or dormant status).

In step 605, the eNB may configure CA or DC based on the measurementresult. The eNB may determine whether to apply CA or DC to the UE basedon the frequency measurement result received from the UE. The UE maydetermine whether there is a SCell or primary SCell (PSCell) to which CAor DC can be applied based on measurement result reported in step 603.The eNB may configure CA or DC when CA or DC can be applied to the UE.Although FIG. 6 illustrates that CA or DC is always performed, CA or DCmay not be performed after it is determined whether to perform CA or DCbased on measurement result according to an embodiment of thedisclosure.

FIG. 7 is a flow diagram of signaling between an eNB and a UE forfrequency measurement and a measurement report in a wirelesscommunication system according to an embodiment. The frequencymeasurement and the measurement report illustrated in FIG. 7 areperformed by the UE in the RRC idle mode or the RRC inactive mode. TheUE corresponds to the UE 135 of FIG. 1 or the UE 315 of FIG. 3. The eNBcorresponds to the eNB 110 of FIG. 1, or the gNB 310 or the eNB 315 ofFIG. 3.

Referring to FIG. 7, operations performed by the UE or the eNB accordingto an embodiment of the disclosure are described below. The UE is in theRRC-connected mode in step 705.

In step 710, the eNB may transmit a signal for controlling the UE, whichtransmits and receives data in the RRC-connected mode, to transition tothe RRC idle mode or the RRC inactive mode. For example, when there isno data transmission and reception for a predetermined time for apredetermined reason, the eNB may transmit an RRC message (for example,RRC connection release, RRC connection suspend, or a new RRC message) tothe UE and control the UE to transition to the RRC idle mode or the RRCinactive mode. That is, when the UE in the RRC-connected modetransitions to the RRC idle mode or the RRC inactive mode, the networkmay transmit the RRC message to instruct the UE to switch the mode. TheRRC message may include information on a frequency to be measured in theRRC idle mode or the RRC inactive mode, a priority of the frequency, anda timer value. It may be more efficient that the network configures thefrequency measurement configuration information in the UE through theRRC message rather than broadcasting the frequency measurementconfiguration information to a cell through system information. This isbecause the network is able to accurately know UE capability in theRRC-connected mode and thus the eNB may configure more suitablefrequency measurement configuration information in the UE.

The RRC message may include various pieces of information. According toan embodiment, the RRC message may include information on a frequencycorresponding to a measurement object or information on a frequency foreach cell (information on cells or frequencies belonging to one eNBsince CA technology supports a plurality of cells or frequenciesbelonging to one eNB), frequency band information, a frequencyidentifier (cell identifier), a measurement value (RSRP, referencesignal received quality (RSRQ), or reference signal to interference andnoise ratio (RS-SINR)) to be measured, a measurement object identifier,a measurement identifier (ID), or a report configuration ID.

The RRC message may include information on an area in which frequencymeasurement should be performed in the RRC idle mode or the RRC inactivemode (for example, a tracking area (TA), a list of cells, a RANnotification area, or a default area information used when there is noarea information). Further, an area or a frequency which the UE shouldmeasure may be indicated by a physical cell ID or an eNB ID.

The RRC message may indicate a physical cell ID or an eNB ID and thusallow the UE to distinguish different cells or eNBs for the samefrequency band in frequency measurement. That is, the UE may performfrequency measurement only for the frequency or the cell correspondingto the configured physical cell ID or eNB ID.

The RRC message may include an indicator indicating whether or not toperform frequency measurement in the RRC idle mode or the RRC inactivemode or whether to perform frequency measurement through frequencyconfiguration information configured as the RRC message or frequencyconfiguration information received as system information.

The RRC message may include information indicating which parameter amongchannel qualities for the frequency is measured and how the parameter ismeasured in frequency measurement in the RRC idle mode or the RRCinactive mode. The channel qualities may be at least one of beam RSRP(BRSRP), RSRP, RSRQ, RSSI, SINR, RS-SINR, carrier to interference andnoise ratio (CINR), signal to noise ratio (SNR), error vector magnitude(EVM), bit error rate (BER), and block error rate (BLER). In the aboveexample, other terms having the equivalent meaning or other metricsindicating channel quality may be used. In the disclosure, high channelquality indicates that a channel quality value related to a size of asignal is large or that a channel quality value related to an error rateis small. When the channel quality is high, a better wirelesscommunication environment may be guaranteed. For example, the RRCmessage may include configuration information indicating measurement ofone or a plurality of RSRP, RSRQ, and RS-SINR.

The RRC message may include information on a maximum number offrequencies (carriers) which can be measured in frequency measurement inthe RRC idle mode or the RRC inactive mode.

The RRC message may configure a time during which the frequencymeasurement is performed to save battery power of the UE. For example,it is possible to save battery power of the UE by setting a timer valueto perform frequency measurement only when the timer is driven and tostop the frequency measurement when the timer expires. That is, the RRCmessage may include a time during which the frequency measurement isperformed in frequency measurement in the RRC idle mode or the RRCinactive mode.

The RRC message may include parameters such as a first time, a secondtime, a number of times, a threshold value, and a period. By configuringthe parameters through the RRC message, the RRC message may indicate atleast one of the following frequency measurement methods. When the UEperforms the frequency measurement based on the parameter values andprovides the measurement report, the UE may report a time stampindicating how long ago or how recently the measurement was performed.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valueis maintained for a predetermined time (the threshold value and the timemay be configured in the UE through the RRC message or may bebroadcasted through system information) and a period is given, the UEmay perform measurement in every corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valueis measured a predetermined number of times or more (the threshold valueand the number of times may be configured in the UE through the RRCmessage or may be broadcasted through system information) and a periodis given, the UE may perform measurement in every corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valuewithin a predetermined time is measured a predetermined number of timesor more (the threshold value and the number of times may be configuredin the UE through the RRC message or may be broadcasted through systeminformation) and a period is given, the UE may perform measurement inevery corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valuewithin a predetermined first time (for example, while a timer is driven)is maintained for a predetermined second time (the threshold value, thefirst time, and the second time may be configured in the UE through theRRC message or may be broadcasted through system information) and aperiod is given, the UE may perform measurement in every correspondingperiod.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valuewithin a predetermined first time (for example, while a timer is driven)is measured a predetermined number of times or more (the thresholdvalue, the first time, and the number of times may be configured in theUE through the RRC message or may be broadcasted through systeminformation) and a period is given, the UE may perform measurement inevery corresponding period.

According to an embodiment, at least one piece of the information on thefrequency measurement included in the RRC message may be broadcastedthrough system information of step 720. In other words, the systeminformation may include pieces of information on the frequencymeasurement. For example, the system information may include informationon a frequency corresponding to a measurement object or information on afrequency for each cell. For example, the system information may includeinformation on which channel quality will be used for frequencymeasurement.

A new indicator may be defined in the RRC message. According to the newindicator, the eNB may indicate to the UE whether or not to performfrequency measurement in the RRC idle mode or the RRC inactive mode orwhether to receive frequency measurement information according to systeminformation and then perform frequency measurement or perform frequencymeasurement based on frequency measurement configuration informationconfigured as the RRC message.

When instructing the UE to transition to the RRC inactive mode throughthe RRC message, the eNB may allocate in advance a security key (forexample, a next hop changing counter (NCC)) to be used for resuming andprovide the security key to the UE. The UE may encrypt information onthe measured frequency result in the RRC inactive mode with the securitykey and report the information to the eNB in the future. By allocatingthe security key in advance, security may be enhanced in re-access ofthe UE and signaling overhead due to security configuration may bereduced. Through the security key configured in advance, whentransmitting message 3 (RRC message, for example, RRC connection resumerequest), the UE may encrypt and transmit the RRC message and decryptreceived decrypted message 4 (RRC message, for example, RRC connectionresume).

A common configuration parameter or a configuration parameter for eachSCell may be introduced to efficiently perform (for example, one time)configuration for a plurality of SCells through the RRC message. The eNBor the UE may use the common configuration parameter or theconfiguration parameter for each of the SCells. When the commonconfiguration parameter and the configuration parameter for each SCellare configured, the configuration for each SCell may have precedenceover the common configuration parameter. For example, a group identifieris defined and then a mapping relation with each SCell identifier may bedefined. That is, one group identifier may be mapped to each of allSCell identifiers and one group identifier may indicate commonconfiguration information of all SCells. Further, a plurality of groupidentifiers may be defined and SCell identifiers mapped to respectivegroup identifiers may be defined, so that configuration information ofcells may be configured in group units. The RRC message may includemapping information with a bandwidth part ID indicating a bandwidth partto be used for the SCell based on the SCell identifier, time/frequencyresource information, or bandwidth part configuration informationcorresponding to each SCell.

According to various embodiments, by defining the indicator in the RRCmessage when making the UE transition to the RRC idle mode or the RRCinactive mode through the RRC message, the eNB may indicate to the UEwhether to store and maintain or discard configuration information ofSCells or the SCell state (activated state, dormant state, ordeactivated state) information in the RRC idle mode or the RRC inactivemode. When mobility of the UE is not large, the UE may directly reusethe configuration information.

In step 715, the UE transitions to the RRC idle mode or the RRC inactivemode according to the indication of the RRC message. In the RRC idlemode or the RRC inactive mode, the UE may perform cell reselectionduring movement.

In step 720, the UE may receive system information of the cell. The UEsearches for a suitable cell based on cell reselection. When a cell onwhich the UE camps is found, the UE receives and reads systeminformation of the cell.

The UE may camp on the cell in the RRC idle mode or the RRC inactivemode and read information on a frequency to be measured in the RRC idlemode or the RRC inactive mode, a priority of the frequency, and timerinformation from the system information of the corresponding cell (forexample, system information block (SIB) 5 in the LTE system and SIB 1,SIB 2, SIB 3, SIB 4, or SIB 5 in the NR system). At least one piece ofthe information included in the RRC message described in step 710 may bebroadcasted as system information of step 720.

According to an embodiment, priorities of the RRC message of step 710and the system information of step 720 may be determined. When frequencymeasurement information to be used in the RRC idle mode or the RRCinactive mode configured in the RRC message meets a first condition, theRRC message may be applied in preference to the system information.

The first condition may be determined by one condition or a combinationof a plurality of conditions below.

The case in which a timer value configured in the RRC message does notexpire.

The case in which the UE does not escape a list of valid cells or anarea to perform frequency measurement configured in the RRC message.

The case in which the UE does not escape a cell which provides a serviceto the UE in the RRC-connected mode.

However, when a second condition is satisfied, the UE may determine thatfrequency measurement information to be used in the RRC idle mode or theRRC inactive mode configured in the RRC message is not valid anymore andpreferentially use the system information for frequency measurement.

The second condition may be determined according to one or a combinationof a plurality of conditions below.

The case in which a timer value configured in the RRC message expires.

The case in which the UE escapes a list of valid cells or an area toperform frequency measurement configured in the RRC message.

The case in which the UE escapes a cell which provides a service to theUE in the RRC-connected mode.

The UE receiving frequency measurement information to be measured in theRRC idle mode or the RRC inactive mode through system information toperform frequency measurement may move and perform cell reselection.When the UE accesses a new cell according to cell reselection, the UEmay receive system information of the new cell. When the systeminformation of the new cell is broadcasted while including frequencymeasurement information to be used in the RRC idle mode or the RRCinactive mode, the UE may receive the new system information andcontinuously perform frequency measurement in the RRC idle mode or theRRC inactive mode. When the system information of the new cell does notinclude frequency measurement information used in the RRC idle mode orthe RRC inactive mode, the UE may stop frequency measurement in order tosave battery power of the UE.

The UE may receive frequency measurement configuration informationthrough an area update procedure. The UE moves while performing cellreselection. The UE may be connected to the network to perform a trackarea update (TAU) procedure when the moving UE is in the RRC idle modeor perform an RAN notification area update (RAN NAU) when the UE is inthe RRC inactive mode. The network may newly configure, in the UE,frequency measurement information to be used in the RRC idle mode or theRRC inactive mode through the RRC message. As described above, when theUE accesses the network in the TAU or RAN NAU update procedure, if thefrequency measurement information is configured in the UE, more suitablefrequency measurement information can be configured for each UE and alsosignaling overhead can be reduced.

In step 725, the UE may perform frequency measurement. The UE in the RRCidle mode or the RRC inactive mode may perform frequency measurementaccording to frequency measurement information configured as the RRCmessage or frequency measurement information configured as systeminformation. The frequency measurement performed by the UE in the RRCidle mode or the RRC inactive mode may include, for example, anoperation for measuring channel quality (for example, RSRP, RSRQ, orRS-SINR) for a frequency instructed to be measured or an operation formeasuring a time during which channel quality of the signal satisfies apredetermined range (for example, exceeds a threshold value). Thefrequency measurement may be referred to as fast frequency measurement.

In step 730, the UE may transmit a random access preamble (RAP). The eNBmay receive a RAP. In step 735, the eNB may transmit a random accessresponse (RAR) in response to the RAP. The UE may receive the RAR.

According to an embodiment, the UE may initiate frequency measurement atvarious time points. That is, the UE may start frequency measurement atone of the time points described below.

The UE may start frequency measurement at a time point at which the UEreceive the RRC message and reads frequency measurement configurationinformation.

The UE may receive the RRC message, read frequency measurementconfiguration information, and start frequency measurement after n timeunits (for example, subframes, time slots, or transmission timeintervals (TTIs)) indicated (or pre-appointed) by the frequencymeasurement configuration information.

The UE may start frequency measurement at a time point at which the UEreceives the system information of step 720 and reads frequencymeasurement configuration information. In an embodiment, the UE mayreceive the system information of step 720, read frequency measurementconfiguration information, and start frequency measurement after n timeunits (for example, subframes, time slots, or TTIs) indicated (orpre-appointed) by the frequency measurement configuration information.

The UE may start frequency measurement at a time point at which apreamble is transmitted for the connection to the network. This isbecause battery power consumption increases if the frequency measurementcontinues even when the connection to the network is not necessary.

The UE may transmit a preamble for the connection to the network andstart frequency measurement at a time point at which a RAR is received.This is because battery power consumption increases if the frequencymeasurement continues even when the connection to the network is notnecessary.

The UE may transmit a preamble for the connection to the network,receive a RAR, and starts frequency measurement at a time point at whichan RRC message (message 3, for example, an RRC connection request or anRRC connection resume request) is transmitted. This is because batterypower consumption increases if the frequency measurement continues evenwhen the connection to the network is not necessary.

The UE may transmit a preamble for the connection to the network,receive a RAR, and start frequency measurement at a time point at whichan RRC message (message 3, for example, an RRC connection request or anRRC connection resume request) is transmitted and message 4 (RRCmessage, for example, RRC connection setup or RRC connection resume) isreceived. This is because battery power consumption increases if thefrequency measurement continues even when the connection to the networkis not necessary.

According to an embodiment, the UE may stop frequency measurementaccording to various conditions. For example, when the UE reportsfrequency measurement, the UE may stop the frequency measurement. Forexample, when transitioning to the RRC-connected mode, the UE may stopthe frequency measurement. For example, when the UE receives an RRCmessage (for example, message 2 (that is, a random access response),message 4 (that is, a contention resolution message)), or a frequencymeasurement request message from the eNB or the UE reports the existenceof a valid frequency measurement result to the eNB, the UE may stop thefrequency measurement.

The frequency measurement performed by the UE in the RRC idle mode orthe RRC inactive mode may be different from the frequency measurementperformed in the RRC-connected mode. That is, when quality of intensityof the current serving cell is less than a predetermined reference (forexample, RSRP, RSRQ, a reception level of the serving cell, or a cellselection quality value (for example, cell selection quality value(Squal))) in the frequency measurement performed in the RRC-connectedmode, the UE initiates measurement of another frequency. That is, thepurpose of the frequency measurement performed in the RRC-connected modeis to move to a better cell and receive a better service if a signal ofthe current serving cell is not good. However, the purpose of thefrequency measurement performed by the UE in the RRC idle mode or theRRC inactive mode is to easily configure carrier aggregation technologyby measuring and reporting another cell regardless of channel quality ofthe current serving cell. While the UE in the RRC-connected mode canperform frequency measurement based on a channel state informationreference signal (CSI-RS) based on a time reference value of the servingcell, the UE in the RRC idle mode or the RRC inactive mode cannotmeasure channel quality (for example, RSRP, RSRQ, or RS-SINR) based on achannel reference signal (CRS) because there is no serving cell. Thatis, the RRC-connected mode and the RRC idle mode or the RRC inactivemode may have different reference signals which are frequencymeasurement objects. With respect to the frequency measurement performedby the UE in the RRC idle mode or the RRC inactive mode, if themeasurement result in the frequency of the serving cell is greater thanSnonIntraSearch and SnonIntraSearchQ (for example, cell selectionreceive (RX) value (Srxlev)>S_(nonIntraSearchP) orSqual>S_(nonIntraSearchQ)), the UE may perform frequency measurement fora frequency of an area, which is not the serving cell (hereinafter,referred to as a non-serving frequency).

Subsequently, the UE which does not currently establish the connection,that is, the UE in the RRC idle mode or the RRC inactive mode mayperform an RRC connection establishment process with the eNB when datato be transmitted is generated. The UE may establish backwardtransmission synchronization with the eNB through a random accessprocess in steps 730 and 735.

In step 740, the UE may transmit an RRCConnectionRequest message to theeNB. The message includes a reason (establishmentCause) to establish theconnection with an identifier of the UE. In step 745, the eNB maytransmit an RRCConnectionSetup message to allow the UE to establish theRRC connection. The message may include RRC connection configurationinformation. The RRC connection is also referred to as a signaling radiobearer (SRB), and is used for transmitting and receiving an RRC messagewhich is a control message between the UE and the eNB. In step 750, theUE establishing the RRC connection may transmit an RRCConnectionSetupmessage to the eNB.

An RRCConnetionSetupComplete message is included in a control message(for example, a service request) making a request by the UE forestablishing a bearer for a predetermined service to the MME. The eNBmay transmit the control message included in theRRCConnetionSetupComplete message to the MME. The MME determines whetherto provide the service requested by the UE. If it is determined toprovide the service requested by the UE based on the determinationresult, the MME transmits a setup request message (for example, aninitial context setup request) to the eNB. The setup request message mayinclude quality of service (QoS) information to be applied toestablishment of the data radio bearer (DRB) and security-relatedinformation to be applied to the DRB (for example, a security key and asecurity algorithm). The eNB may transmit a security configurationmessage (for example, SecurityModeCommand) to configure security withthe UE in step 755 and transmit a security configuration completionmessage (for example, SecurityModeComplete) to inform the eNB ofsecurity configuration in step 760, which completes the securityconfiguration procedure.

The UE may report a valid frequency measurement result to the eNB. Thatis, if there is a valid frequency measurement result which satisfies apredetermined condition for the SCell, the UE in the RRC idle mode orthe RRC inactive mode may report the valid measurement result value tothe eNB when establishing the connection to the network. For example,the UE may report the existence of the valid frequency measurementresult value to the eNB through message 3 (for example, an RRC message,an RRC connection request, an RRC connection resume request, or a newRRC message) or message 5 (for example, an RRC message, an RRCconnection setup complete, an RRC connection resume complete, or a newRRC message). According to a definition of a new indicator or aninformation element (IE) in the RRC message, the existence of the validfrequency measurement result value may be indicated. Further, accordingto allocation of a logical channel identifier (LCID) used by the MAClayer, a MAC control element may indicate the existence of the validfrequency measurement result value.

The eNB may make a request for reporting the measurement result to theUE. When the eNB knows that there is the valid frequency measurementresult measured by the UE in the RRC idle mode or the RRC inactive mode,the eNB may make a request for reporting the measurement result to theUE as necessary. The measurement result report may be requested throughvarious methods. According to an embodiment, the eNB may make a requestfor reporting the measurement result by transmitting an indicatorthrough message 2 (RAR) or message 4. The eNB may make a request forreporting the measurement result by transmitting an RRC message for aseparate measurement report request (a new RRC message or aconventionally defined RRC message, for example, a measurement reportcommand) after security configuration is completed. New MAC controlinformation for the measurement report request may be defined and a newlogical channel identifier is defined. The eNB may make a request forthe measurement report by transmitting the MAC control information tothe UE.

When the UE receives the measurement report request from the eNB, the UEmay transmit the measurement result. The UE may encrypt the measurementresult through the configured security configuration information andtransmit the encrypted measurement result. If the report of thefrequency measurement result is not encrypted, the frequency measurementinformation may be hacked or leaked and the location of the UE may betracked based on the frequency measurement report and thus personalinformation may be exposed. Accordingly, it is required to perform thefrequency measurement report after encryption. The UE may transmit thefrequency measurement result to the eNB through an RRC message (a newRRC message or a conventionally defined RRC message, for example, ameasurement report). Alternatively, new MAC control information for themeasurement report is defined and a new logical channel identifier isdefined, and thus the UE may provide the measurement report bytransmitting the MAC control information to the eNB.

According to an embodiment, a random access procedure may be used forthe valid frequency measurement result and the request and report of thefrequency measurement result. Preambles of message 1 may be grouped.Among the grouped preambles, particular preambles may indicate theexistence of the measurement report result. The UE may inform the eNBthat there is the valid frequency measurement result by transmittingpreamble(s) corresponding to a particular group. The UE may identifywhether there is a request for the measurement result by receiving theRAR (message 2) from the eNB. When the report of the measurement resultis requested by the RAR (for example, the existence of an indicator),the UE may report the measurement result through message 3. The eNB maytransmit an RRC configuration message for configuring the SCell based onthe measurement result to the UE.

When there is the valid frequency measurement result report, the UE mayreport the frequency measurement result to the eNB. That is, when thereis the valid frequency measurement result report, the UE may transmitthe report of the frequency measurement result to the eNB even throughthere is no request from the eNB. The UE may transmit the frequencymeasurement result to the eNB through an RRC message (a new RRC message,a conventionally defined RRC message, message 3, or message 5, forexample, a measurement report). As new MAC control information for themeasurement report is defined and a new logical channel identifier isdefined, the UE may provide the measurement report by transmitting MACcontrol information to the eNB.

The UE may transmit a necessary frequency measurement result among allfrequency measurement results to the network (eNB). The UE performingthe frequency measurement in the RRC idle mode or the RRC inactive modemay report the frequency measurement result for carriers (SCell), towhich CA can be applied, to the network. The UE may report themeasurement result only for the SCell satisfying a predeterminedcondition. In other words, the SCell to which CA can be applied is theSCell satisfying the predetermined condition.

The UE may report the frequency measurement result for the SCellsatisfying the predetermined condition to the network based onmeasurement of the UE. If a period is given, the UE may performmeasurement in every corresponding period. The predetermined conditionmay include at least one of the following conditions.

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value is maintained for a predetermined time, the condition issatisfied (the threshold value and the time may be configured in the UEthrough an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value is measured a predetermined number of times or more, thecondition is satisfied (the threshold value and the number of times maybe configured in the UE through an RRC message or may be broadcastedthrough system information).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater, than a predeterminedthreshold value within a predetermined time is measured a predeterminednumber of times or more, the condition is satisfied (the thresholdvalue, the time, and the number of times may be configured in the UEthrough an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a first time (for example, while a timer isdriven) is maintained for a second time, the condition is satisfied (thethreshold value, the first time, and the second time may be configuredin the UE through an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a first time (for example, while a timer isdriven) is measured a predetermined number of times or more, thecondition is satisfied (the threshold value, the first time, and thenumber of times may be configured in the UE through an RRC message ormay be broadcasted through system information).

When the frequency measured by the UE in the RRC idle mode or the RRCinactive mode is a cell or a frequency indicated by system informationof the serving cell which the UE accesses, the condition is satisfied,CA technology can be supported for a plurality of cells served by oneeNB, so that the CA technology cannot be applied no matter how good asignal of a cell served by another eNB is. Accordingly, the frequencymeasurement result measured by the UE can be used for application of thecarrier aggregation technology only when the frequency measurementresult is a measurement result for the cell which the UE accesses or thefrequency supported by the eNB). For example, when the frequency is afrequency or a cell belonging to a cell list indicated by systeminformation (white cell list), the corresponding frequency or cellsatisfies the condition.

When the eNB does not know UE capability of the UE currently having theestablished connection or when the eNB is required to identify UEcapability, the eNB may transmit a message (for example, a UE capabilityenquiry) asking of UE capability. The UE may transmit a message (forexample, UE capability) reporting its own capability. Through themessage, the UE may report information on whether frequency measurementcan be performed in the RRC idle mode or the RRC inactive mode orinformation on frequencies or a frequency area which can be measured ora maximum number of frequencies which can be measured to the eNB.

In step 770, the eNB may transmit an RRCConnectionReconfigurationmessage to the UE. When security configuration is completed according tosteps 755 and 760, the eNB may transmit an RRCConnectionReconfigurationmessage to the UE. The message may include configuration information ofthe DRB for processing user data. The UE may receive configurationinformation of the DRB. Before transmitting a reconfiguration message(RRCConnectionReconfiguration), the eNB may transmit a measurementreport request (measurement report command) and the UE may transmit ameasurement report in step 765.

In step 775, the UE may transmit an RRCConnectionReconfigurationCompletemessage to the eNB. The UE may establish the DRB by applying theconfiguration information of the DRB received in step 770 and transmitthe RRCConnectionReconfigurationComplete message to the eNB.

According to an embodiment, a common configuration parameter or aconfiguration parameter for each SCell may be introduced to efficientlyperform (for example, one time) configuration for a plurality of SCellsthrough the RRC message (RRC connection reconfiguration) of step 770.The eNB or the UE may use the common configuration parameter or theconfiguration parameter for each of the SCells. When the commonconfiguration parameter and the configuration parameter for each SCellare configured, the configuration for each SCell may have precedenceover the common configuration parameter. For example, a group identifieris defined and then a mapping relation with each SCell identifier may bedefined. That is, one group identifier may be mapped to each of allSCell identifiers and one group identifier may indicate commonconfiguration information of all SCells. Further, a plurality of groupidentifiers may be defined and SCell identifiers mapped to respectivegroup identifiers may be defined, so that configuration information ofcells may be configured in group units. The RRC message may includemapping information with a bandwidth part ID indicating a bandwidth partto be used for the SCell based on the SCell identifier, time/frequencyresource information, or bandwidth part configuration informationcorresponding to each SCell. After transmitting the RRC reconfigurationmessage (RRCConnectionReconfiguration), the eNB may transmit ameasurement report request (measurement report command) and the UE maytransmit a measurement report in step 780.

When the SCells are configured in the RRC message, an initial state ofthe SCell may be configured as an activated state, a dormant state, or adeactivated state. If the SCells are configured to have an initial statecorresponding to an activated state or a dormant state whenconfiguration information of the SCells is transmitted, the UE maydirectly perform and report frequency measurement for the SCells, sothat the eNB may rapidly apply the CA technology. Transition to theactivated state, the dormant state, or the deactivated state of eachSCell may be indicated to the UE in the RRC-connected mode through MACcontrol information. When the SCell is in the activated state or thedormant state, the UE in the RRC-connected mode may perform frequencymeasurement and report the frequency measurement result to the eNB. Thefrequency measurement report may be provided through an RRC message orMAC control information. When the state of each SCell is configured asthe activated state or the dormant state through the RRC message, the UEmay be configured according to configuration information including aninteger indicating when physical downlink control channel (PDCCH)monitoring is started and when report of the frequency (channel or cell)measurement result is started. For example, the UE may start PDCCHmonitoring or the measurement result report after time units (forexample, subframes, time slots, or TTIs) corresponding to the indicatedinteger.

The eNB completing establishment of the DRB with the UE transmits aninitial context setup complete message to the MME. The MME receiving themessage exchanges an S1 bearer setup message and an S1 bearer setupresponse message with the S-GW in order to establish an S1 bearer. TheS1 bearer is a connection for data transmission established between theS-GW and the eNB and corresponds to the DRB in one-to-onecorrespondence. When the processor is completed, the UE transmits andreceives data through the eNB and the S-GW. Further, the eNB maytransmit an RRCConnectionReconfiguration message in order to provide newconfiguration to the UE or add or change the configuration for apredetermined reason.

In this disclosure, a cell and a carrier may indicate the same meaning.An SCell denotes a secondary cell. When CA is used, more data may betransmitted and received through additional carriers or cells as well asa primary cell (Pcell) receiving and transmitting control signal betweenthe eNB and the UE, and the additional carriers or cells may be referredto as SCells. According to an embodiment, a serving cell may include theSCell.

The frequency measurement procedure and the frequency configurationinformation in the RRC idle mode or the RRC inactive mode in thedisclosure may extend to be applied to the UE in the RRC-connected mode.The frequency measurement procedure and the frequency configurationinformation in the RRC idle mode or the RRC inactive mode in thedisclosure may be applied and performed independently from the frequencymeasurement procedure performed by the UE in the RRC idle mode or theRRC inactive mode when the UE performs the cell reselection procedure.According to an embodiment, since there is a maximum number offrequencies which can be measured according to UE capability, the eNBmay set configuration information of the frequency measurement method inconsideration of the UE capability.

FIG. 8 is a flow diagram of signaling between an eNB and an UE forfrequency measurement and a measurement report in a wirelesscommunication system according to an embodiment. The frequencymeasurement and the measurement report are performed by the UE in theRRC inactive mode. The UE corresponds to the UE 135 of FIG. 1 or the UE315 of FIG. 3. The eNB corresponds to the eNB 110 of FIG. 1, the gNB310, or the eNB 315 of FIG. 3.

Referring to FIG. 8, an embodiment performed by the UE or the eNB isdescribed below. The UE is in the RRC-connected mode in step 805.

In step 810, the eNB may transmit a signal for controlling the UE, whichtransmits and receives data in the RRC-connected mode, to transition tothe RRC inactive mode. For example, when there is no data transmissionand reception for a predetermined reason or for a predetermined time,the eNB may transmit an RRC message (for example, an RRC connectionrelease, an RRC connection suspend, or a new RRC message) to the UE andcontrol the UE to transition to the RRC inactive mode in step 815. Thatis, when the UE in the RRC-connected mode transitions to the RRCinactive mode, the network may transmit the RRC message to instruct theUE to switch the mode. The RRC message may include information on afrequency to be measured in the RRC inactive mode, a priority of thefrequency, and a timer value. According to an embodiment, it may be moreefficient that the network configures the frequency measurementconfiguration information in the UE through the RRC message rather thanbroadcasting the frequency measurement configuration information to acell through system information. This is because the network is able toaccurately know UE capability in the RRC-connected mode and thus the eNBmay configure more suitable frequency measurement configurationinformation in the UE.

The RRC message may include various pieces of information. The RRCmessage may include information on a frequency corresponding to ameasurement object or information on a frequency for each cell(information on cells or frequencies belonging to one eNB since CAtechnology supports a plurality of cells or frequencies belonging to oneeNB), frequency band information, a frequency identifier (cellidentifier), a measurement value (RSRP, RSRQ, or RS-SINR) to bemeasured, a measurement object identifier, a measurement ID, or a reportconfiguration ID.

The RRC message may include information on an area in which frequencymeasurement is performed in the RRC inactive mode (for example, a TA, alist of cells, a RAN notification area (RNA), or default areainformation used when there is to area information). Further, an area ora frequency which the UE should measure may be indicated by a physicalcell ID or an eNB ID.

The RRC message may indicate a physical cell identifier or an eNBidentifier and thus allow the UE to distinguish different cells or eNBsfor the same band in frequency measurement. That is, the UE may performfrequency measurement only for the frequency or the cell correspondingto the configured physical cell ID or eNB ID.

The RRC message may include an indicator indicating whether or not toperform frequency measurement in the RRC inactive mode or whether toperform frequency measurement through frequency configurationinformation configured as the RRC message or frequency configurationinformation received as system information.

The RRC message may include information indicating which parameter amongchannel qualities for the frequency is measured and how the parameter ismeasured in frequency measurement in the RRC inactive mode. For example,the RRC message may include configuration information indicatingmeasurement of one or a plurality of RSRP, RSRQ, and RS-SINR.

The RRC message may include information on a maximum number offrequencies (carriers) which can be measured in frequency measurement inthe RRC inactive mode.

The RRC message may configure a time during which the frequencymeasurement is performed to save battery power of the UE. For example,it is possible to save battery power of the UE by setting a timer valueto perform frequency measurement only when the timer is driven and tostop the frequency measurement when the timer expires. That is, the RRCmessage may include a time during which frequency measurement isperformed in the RRC inactive mode.

The RRC message may include parameters such as a first time, a secondtime, a number of times, a threshold value, or a period. By configuringthe parameters, the RRC message may indicate at least one of thefollowing frequency measurement methods. When the UE performs thefrequency measurement based on the parameter values and provides themeasurement report, the UE may report a time stamp indicating how longago or how recently the measurement was performed.

A state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valueis maintained for a predetermined time (the threshold value and the timemay be configured in the UE through the RRC message or may bebroadcasted through system information). When a period is given, the UEmay perform measurement in every corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valueis measured a predetermined number of times or more (the threshold valueand the number of times may be configured in the UE through the RRCmessage or may be broadcasted through system information) and a periodis given, the UE may perform measurement in every corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valuewithin a predetermined time is measured a predetermined number of timesor more (the threshold value and the number of times may be configuredin the UE through the RRC message or may be broadcasted through systeminformation) and a period is given, the UE may perform measurement inevery corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valuewithin a predetermined first time is maintained for a predeterminedsecond time (the threshold value and the time may be configured in theUE through the RRC message or may be broadcasted through systeminformation) and a period is given, the UE may perform measurement inevery corresponding period.

When a state in which the channel quality of the frequency (for example,RSRP, RSRQ, or RS-SINR) is greater than a predetermined threshold valuewithin a predetermined first time (for example, while a timer is driven)is measured a predetermined number of times or more (the thresholdvalue, the first time, and the number of times may be configured in theUE through the RRC message or may be broadcasted through systeminformation) and a period is given, the UE may perform measurement inevery corresponding period.

According to an embodiment, a new indicator may be defined in the RRCmessage. According to the new indicator, the eNB may indicate to the UEwhether or not to perform frequency measurement in the RRC inactive modeor whether to receive frequency measurement information according tosystem information and then perform frequency measurement or performfrequency measurement based on frequency measurement configurationinformation configured as the RRC message.

When instructing the UE to transition to the RRC inactive mode throughthe RRC message, the eNB may allocate in advance a security key (forexample, an NCC) to be used for resuming and provide the security key tothe UE. The UE may encrypt information on the measured frequency resultin the RRC inactive mode with the security key and report theinformation to the eNB in the future. By allocating the security key inadvance, security may be enhanced in re-access of the UE and signalingoverhead due to security configuration may be reduced. Through thesecurity key configured in advance, when transmitting message 3 (RRCmessage, for example, RRC connection resume request), the UE may encryptand transmit the RRC message and decrypt received decrypted message 4(RRC message, for example, RRC connection resume).

A common configuration parameter or a configuration parameter for eachSCell may be introduced to efficiently perform (for example, one time)configuration for a plurality of SCells through the RRC message. The eNBor the UE may use the common configuration parameters or theconfiguration parameter for each of the SCells. When the commonconfiguration parameter and the configuration parameter for each SCellare configured, the configuration for each SCell may have precedenceover the common configuration parameter. For example, a group identifieris defined and then a mapping relation with each SCell identifier may bedefined. That is, one group identifier may be mapped to each of allSCell identifiers and one group identifier may indicate commonconfiguration information of all SCells. Further, a plurality of groupidentifiers may be defined and SCell identifiers mapped to respectivegroup identifiers may be defined, so that configuration information ofcells may be configured in group units. The RRC message may includemapping information with a bandwidth part ID indicating a bandwidth partto be used for the SCell based on the SCell identifier, time/frequencyresource information, or bandwidth part configuration informationcorresponding to each SCell.

By defining the indicator in the RRC message when making the UEtransition to the RRC inactive mode through the RRC message, the eNB mayindicate to the UE whether to store and maintain or discardconfiguration information of SCells or the SCell state (activated state,dormant state, or deactivated state) information in the RRC idle mode orthe RRC inactive mode. When mobility of the UE is not great, the UE maydirectly reuse the configuration information.

In step 815, the UE transitions to the RRC inactive mode according tothe indication of the RRC message. In the RRC inactive mode, the UE mayperform cell reselection during movement.

In step 820, the UE may receive system information of the cell. The UEsearches for a suitable cell based on cell reselection. When a cell onwhich the UE camps is found, the UE receives and reads systeminformation of the cell.

The UE may camp on the cell in the RRC inactive mode and readinformation on a frequency to be measured in the RRC inactive mode, apriority of the frequency, and timer information from the systeminformation of the corresponding cell (for example, SIB 5 in the LTEsystem and SIB 1, SIB 2, SIB 3, SIB 4, or SIB 5 in the NR system). Atleast one piece of the information included in the RRC message describedin step 810 may be broadcasted through the system information of step820.

According to an embodiment, priorities of the RRC message of step 810and the system information of step 820 may be determined. When frequencymeasurement information to be used in the RRC inactive mode configuredin the RRC message meets a first condition, the RRC message may beapplied in preference to the system information of step 820.

The first condition may be determined by one or a combination of aplurality of conditions below.

The case in which a timer value configured in the RRC message does notexpires.

The case in which the UE does not escape a list of valid cells or anarea to perform frequency measurement configured in the RRC message.

The case in which the UE does not escape a cell which provides a serviceto the UE in the RRC-connected mode.

However, when a second condition is satisfied, the UE may determine thatfrequency measurement information to be used in the RRC inactive modeconfigured in the RRC message is not valid and preferentially use thesystem information for frequency measurement.

The second condition may be determined according to one or a combinationof a plurality of conditions below.

The case in which a timer value configured in the RRC message expires.

The case in which the UE escapes a list of valid cells or an area toperform frequency measurement configured in the RRC message.

The case in which the UE escapes a cell which provides a service to theUE in the RRC-connected mode.

The UE receiving frequency measurement information to be used in the RRCinactive mode to perform frequency measurement may move and perform cellreselection. When the UE accesses a new cell according to cellreselection, the UE may receive system information of the new cell. Whenthe system information of the cell is broadcasted while includingfrequency measurement information to be used in the RRC inactive mode,the UE may receive new system information and continuously performfrequency measurement in the RRC inactive mode. When the systeminformation of the new cell does not include frequency measurementinformation used in the RRC inactive mode, the UE may stop frequencymeasurement in order to save battery power of the UE.

The UE may receive frequency measurement configuration informationthrough an area update procedure. The UE moves while performing cellreselection. The UE may be connected to the network to perform a TAUprocedure when the moving UE is in the RRC idle mode or perform an RANNAU when the UE is in the RRC inactive mode. The network may newlyconfigure, in the UE, frequency measurement information to be used inthe RRC inactive mode through the RRC message. As described above, whenthe UE accesses the network in the TAU or RAN NAU update procedure, ifthe frequency measurement information is configured in the UE, moresuitable frequency measurement information can be configured for each UEand also signaling overhead can be reduced.

In step 825, the UE may perform frequency measurement. The UE in the RRCinactive mode may perform frequency measurement according to frequencymeasurement information configured as the RRC message or frequencymeasurement information configured as system information.

The frequency measurement performed by the UE in the RRC inactive modemay include, for example, an operation for measuring channel quality(for example, RSRP, RSRQ, or RS-SINR) for a frequency instructed to bemeasured or an operation for measuring a time during which channelquality of the signal satisfies a predetermined range (for example,exceeds a threshold value).

In step 830, the UE may transmit a RAP. The eNB may receive a RAP. Instep 835, the eNB may transmit a RAR in response to the RAP. The UE mayreceive the RAR.

According to an embodiment, the UE may initiate frequency measurement atvarious time points. That is, the UE may start frequency measurement atone of the time points described below.

The UE may start frequency measurement at a time point at which the UEreceives the RRC message of step 810 and reads frequency measurementconfiguration information.

The UE may receive the RRC message of step 810, read frequencymeasurement configuration information, and start frequency measurementafter n time units (for example, subframes, time slots, or TTIs)indicted by (or pre-appointed in) the frequency measurementconfiguration information.

The UE may start frequency measurement at the time point at which the UEreceives the system information of step 820 and read the frequencymeasurement configuration information.

The UE may receive the system information, read the frequencymeasurement configuration information, and start frequency measurementafter n time units (for example, subframes, time slots, or TTIs)indicated (or pre-appointed) by the frequency measurement configurationinformation.

The UE may start frequency measurement at a time point at which apreamble is transmitted for the connection to the network. This isbecause battery power consumption increases if the frequency measurementcontinues even when the connection to the network is not necessary.

The UE may transmit a preamble for the connection to the network andstart frequency measurement at a time point at which a RAR is received.This is because battery power consumption increases if the frequencymeasurement continues even when the connection to the network is notnecessary.

The UE may transmit a preamble for the connection to the network andstarts frequency measurement at a time point at which an RRC message(message 3, for example, an RRC connection request or an RRC connectionresume request) is transmitted. This is because battery powerconsumption increases if the frequency measurement continues even whenthe connection to the network is not necessary.

The UE may transmit a preamble for the connection to the network,receive a RAR, and start frequency measurement at a time point at whichan RRC message (message 3, for example, an RRC connection request or anRRC connection resume request) is transmitted and message 4 (RRCmessage, for example, RRC connection setup or RRC connection resume) isreceived. This is because battery power consumption increases if thefrequency measurement continues even when the connection to the networkis not necessary.

The UE may stop frequency measurement according to various conditions.For example, when the UE reports frequency measurement, the UE may stopthe frequency measurement. For example, when transitioning to theRRC-connected mode, the UE may stop the frequency measurement. Forexample, when the UE receives an RRC message (for example, message 2(that is, a random access response), message 4 (that is, a contentionresolution message), or a frequency measurement request message from theeNB or the UE reports the existence of a valid frequency measurementresult to the eNB, the UE may stop the frequency measurement.

According to an embodiment, frequency measurement performed by the UE inthe RRC inactive mode may be different from frequency measurementperformed in the RRC-connected mode. That is, when quality or intensityof the current serving cell is less than a predetermined reference (forexample, RSRP, RSRQ, a reception level (for example, Srxlev) of theserving cell, or a serving cell selection quality value (for example,Squal)) in the frequency measurement performed in the RRC-connectedmode, the UE initiates measurement of another frequency. That is, thepurpose of the frequency measurement performed in the RRC-connected modeis to move to a better cell and receive a better service if a signal ofthe current serving cell is not good. However, the purpose of thefrequency measurement performed by the UE in the RRC inactive mode is toconfigure carrier aggregation technology by measuring and reportinganother cell regardless of channel quality of the current serving cell.While the UE in the RRC-connected mode can perform frequency measurementbased on a CSI-RS based on a time reference value of the serving cell,the UE in the RRC idle mode or the RRC inactive mode cannot measurechannel quality (for example, RSRP, RSRQ, or RS-SINR) based on a CSI CRSbecause there is no serving cell. That is, the RRC-connected mode andthe RRC inactive mode may have different reference signals which arefrequency measurement objects. With respect to the frequency measurementperformed by the UE in the RRC inactive mode, although the measurementresult in the frequency of the serving cell is greater thanSnonIntraSearch and SnonIntraSearchQ (for example,Srxlev>S_(nonIntraSearchP) or Squal>S_(nonIntraSearchQ)) indicated bysystem information, the UE may perform frequency measurement for afrequency of an area, which is not the serving cell, that is, anon-serving frequency.

Subsequently, the UE which does not currently establish the connection,that is, the UE in the RRC inactive mode may perform an RRC connectionresume process with the eNB when data to be transmitted is generated.The UE may establish backward transmission synchronization with the eNBthrough a random access process in steps 830 and 835.

In step 840, the UE may transmit an RRCConnectionResumeRequest messageto the eNB. The message includes a reason (establishmentCause) toestablish the connection with an identifier of the UE. In step 845, theeNB may transmit an RRCConnectionResume message to allow the UE toestablish the RRC connection. The message may include RRC connectionconfiguration information. As described above, the RRC connection isreferred to as an SRB and is used for transmission and reception of theRRC message which is a control message between the UE and the eNB. Instep 850, the UE establishing the RRC connection may transmit anRRCConnetionResumeComplete message to the eNB.

According to an embodiment, the UE may report a valid frequencymeasurement result to the eNB. That is, if there is a valid frequencymeasurement result which satisfies a predetermined condition for theSCell, the UE in the RRC inactive mode may report the valid measurementresult value to the eNB when establishing the connection to the network.For example, the UE may report the existence of the valid frequencymeasurement result value to the eNB through message 3 (for example, anRRC message, an RRC connection request, an RRC connection resumerequest, or a new RRC message) or message 5 (for example, an RRCmessage, an RRC connection setup complete, an RRC connection resumecomplete, or a new RRC message). The existence of a valid frequencymeasurement result value may be indicated by definition of a newindicator or an IE in the RRC message to indicate the existence of thevalid frequency measurement result value. The existence of a validfrequency measurement result value may be indicated by MAC controlinformation through allocation of a logical channel identifier used bythe MAC layer.

The eNB may make a request for reporting the measurement result to theUE. When the eNB knows that there is a valid frequency measurementresult measured by the UE in the RRC inactive mode, the eNB may make arequest for reporting the measurement result to the UE as necessary. Themeasurement result report may be requested through various methods. TheeNB may make a request for reporting the measurement result bytransmitting an indicator through message 2 (RAR) or message 4. The eNBmay make a request for reporting the measurement result by transmittingan RRC message for a separate measurement report request (a new RRCmessage, a conventionally defined RRC message, or a measurement reportcommand) to the UE after security configuration is completed. New MACcontrol information for the measurement report request may be definedand a new logical channel identifier is defined. The eNB may make arequest for the measurement report by transmitting the MAC controlinformation to the UE.

When the UE receives the measurement report request from the eNB, the UEmay transmit the measurement result. The UE may encrypt the measurementresult through security configuration information configured with thenetwork and transmit the encrypted measurement result. If the report ofthe frequency measurement result is not encrypted, the frequencymeasurement information may be hacked or leaked and the location of theUE may be tracked based on the frequency measurement report and thuspersonal information may be exposed. Accordingly, it is required toperform the frequency measurement report after encryption. The UE maytransmit the frequency measurement result to the eNB through an RRCmessage (a new RRC message or a conventionally defined RRC message, forexample, a measurement report). Alternatively, new MAC controlinformation for the measurement report is defined and a new logicalchannel identifier is defined, and thus the UE may provide themeasurement report by transmitting the MAC control information to theeNB.

According to an embodiment, a random access procedure may be used forthe valid frequency measurement result and the request and report of thefrequency measurement result. Preambles of message 1 may be grouped.Among the grouped preambles, particular preambles may indicate theexistence of the measurement report result. The UE may inform the eNBthat there is the valid frequency measurement result by transmittingpreamble(s) corresponding to a particular group. When the RAR, which ismessage 2, includes an indicator indicating the report of themeasurement result, the UE may identify whether there is a request forthe measurement result. When the report of the measurement result isrequested by the RAR, the UE may report the measurement result throughmessage 3. The eNB may transmit an RRC configuration message forconfiguring the SCell based on the measurement result to the UE.

When there is a valid frequency measurement result report, the UE mayreport the frequency measurement result to the eNB. That is, when thereis the valid frequency measurement result report, the UE may transmitthe report of the frequency measurement result to the eNB even throughthere is no request from the eNB. The UE may transmit the frequencymeasurement result to the eNB through an RRC message (a new RRC message,a conventionally defined RRC message, message 3, or message 5, forexample, a measurement report). As new MAC control information for themeasurement report is defined and a new logical channel identifier isdefined, the UE may provide the measurement report by transmitting MACcontrol information to the eNB.

The UE may transmit a necessary frequency measurement result among allfrequency measurement results to the network (eNB). The UE performingthe frequency measurement in the RRC inactive mode may report thefrequency measurement result for carriers (SCell), to which CA can beapplied, to the network. The UE may report the measurement result onlyfor the SCell satisfying a predetermined condition. In other words, theSCell to which CA can be applied is the SCell satisfying thepredetermined condition.

The UE may report the frequency measurement report for the SCellsatisfying the predetermined condition to the network based onmeasurement of the UE. If a period is given, the UE may performmeasurement in every corresponding period. The predetermined conditionmay include at least one of the following conditions.

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value is maintained for a predetermined time, the condition issatisfied (the threshold value and the time may be configured in the UEthrough an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value is measured a predetermined number of times or more, thecondition is satisfied (the threshold value and the number of times maybe configured in the UE through an RRC message or may be broadcastedthrough system information).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a predetermined time is measured a predeterminednumber of times or more, the condition is satisfied (the thresholdvalue, the time, and the number of times may be configured in the UEthrough an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a first time (for example, while a timer isdriven) is maintained for a second time, the condition is satisfied (thethreshold value, the first time, and the second time may be configuredin the UE through an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a first time (for example, while a timer isdriven) is measured a predetermined number of times or more, thecondition is satisfied (the threshold value, the first time, and thenumber of times may be configured in the UE through an RRC message ormay be broadcasted through system information).

When the frequency measured by the UE in the RRC inactive mode is a cellor a frequency indicated by system information of the serving cell whichthe UE accesses, the condition is satisfied CA technology can besupported for a plurality of cells served by one eNB, so that the CAtechnology cannot be applied no matter how good a signal of a cellserved by another eNB is. Accordingly, the frequency measurement resultmeasured by the UE can be used for application of the carrieraggregation technology only when the frequency measurement result is ameasurement result for the cell which the UE accesses or the frequencysupported by the eNB). For example, when the frequency is a frequency ora cell belonging to a cell list indicated by system information (whitecell list), the corresponding frequency or cell satisfies the condition.

When the eNB does not know UE capability of the UE currently having theestablished connection or when the eNB is required to identify UEcapability, the eNB may transmit a message (for example, a UE capabilityenquiry) asking of UE capability. The UE may transmit a message (forexample, UE capability) reporting its own capability. Through themessage, the UE may report information on whether frequency measurementcan be performed in the RRC idle mode or the RRC inactive mode orinformation on frequencies or a frequency area which can be measured ora maximum number of frequencies which can be measured to the eNB.

According to an embodiment, a common configuration parameter or aconfiguration parameter for each SCell may be introduced to efficientlyperform (for example, one time) configuration for a plurality of SCellsthrough the RRC message (RRC connection reconfiguration) of step 845.The eNB or the UE may use common configuration parameters or introduce aconfiguration parameter for each of the SCells. The eNB or the UE mayuse the common configuration parameters or the configuration parameterfor each of the SCells. When the common configuration parameter and theconfiguration parameter for each SCell are configured, the configurationfor each SCell may have precedence over the common configurationparameter. For example, a group identifier is defined and then a mappingrelation with each SCell identifier may be defined. That is, one groupidentifier may be mapped to each of all SCell identifiers and one groupidentifier may indicate common configuration information of all SCells.Further, a plurality of group identifiers may be defined and SCellidentifiers mapped to respective group identifiers may be defined, sothat configuration information of cells may be configured in groupunits. The RRC message may include mapping information with a bandwidthpart ID indicating a bandwidth part to be used for the SCell based onthe SCell identifier, time/frequency resource information, or bandwidthpart configuration information corresponding to each SCell.

When the SCells are configured in the RRC message, an initial state ofthe SCell may be configured as an activated state, a dormant state, or adeactivated state. If the SCells are configured to have an initial statecorresponding to an activated state or a dormant state whenconfiguration information of the SCells is transmitted, the UE maydirectly perform and report frequency measurement for the SCells, sothat the eNB may rapidly apply the CA technology. Transition to theactivated state, the dormant state, or the deactivated state of eachSCell may be indicated to the UE in the RRC-connected mode through MACcontrol information. When the SCell is in the activated state or thedormant state, the UE in the RRC-connected mode may perform frequencymeasurement and report the frequency measurement result to the eNB. Thefrequency measurement report may be provided through an RRC message orMAC control information. When the state of each SCell is configured asthe activated state or the dormant state through the RRC message, the UEmay be configured according to configuration information including aninteger indicating when PDCCH monitoring is started and when thefrequency (channel or cell) measurement result is reported. For example,the UE may start PDCCH monitoring or the measurement result report aftertime units (for example, subframes, time slots, or TTIs) correspondingto the indicated integer.

According to an embodiment, the eNB may transmit an RRC ConnectionReconfiguration message again in order to provide new configuration tothe UE or add or change the configuration for a predetermined reason.The RRC Connection Reconfiguration message may be transmitted whileincluding information which can be included in the RRC connection resumeor a portion of the information.

Hereinafter, operations of the UE according to an embodiment illustratedin FIG. 8 are indicated.

The RRC message of step 810 of FIG. 8 may include configurationinformation of a measurement-related parameter for measuring an inactivestate. That is, the measurement-related parameter may be configured in acontrol message indicating transition to the inactive state.

Inactive State Parameter:

Identity radio network temporary identifier (I-RNTI): I-RNTI may be usedas an identifier of the UE when the connection to the network isreconfigured and may be referred to as a resume ID. The I-RNTI may beused for identifying the existence or non-existence of paging when apaging message is received.

RNA: RNA may indicate an area of a network supporting an inactive modewhen the UE transitions to the inactive mode. When the UE escapes apredetermined area by an RNA, the UE should report its own location tothe network and perform a procedure for receiving a new area.

Inactive State First Measurement-Related Parameter:

A frequency to be measured and a measurement period.

An NR evolved absolute radio frequency channel number (EARFCN) list anda measurement period for each NR-EARFCN.

If a measurement period is n, measurement is performed in everyn*discontinuous reception (DRX) cycle.

If a measurement period is not configured, n=1.

L3 filtering coefficient (measurement coefficient to be used infrequency measurement).

Valid timer (frequency measurement is performed only while a timer isdriven according to a configured timer value).

Measurement result report condition.

Integer m, RSRP/RSRQ threshold value, time period d.

For example, if all of m measurement results are greater than an RSRPthreshold value or an RARQ threshold value, a condition is satisfied.

For example, if all measurement results are greater than an RSRPthreshold value or an RARQ threshold value during a time period of d, acondition is satisfied.

For example, if a state in which all of m measurement results aregreater than an RSRP threshold value or an RARQ threshold value ismaintained for a time period of d, a condition is satisfied.

Measurement area (which is the same as an RAN if the measurement area isnot signaled).

In step 825, the UE may perform the following frequency measurement inthe RRC inactive mode. The UE may perform frequency measurement duringthe inactive state.

When a first condition is satisfied, the UE performs a first measurementoperation. Satisfaction of the first condition may be determinedaccording to a validity timer. For example, the validity timer for thefirst condition is driven. The first condition is satisfied if thevalidity timer is being driven. Driving of the validity timer isinitiated when the UE transitions to the RRC inactive mode, that is, theinactive state. When the UE transitions to the inactive state, the UEinitiates the first measurement operation. The validity timer is stoppedor reset when a particular condition is satisfied. For example, when theUE escapes the RNA or the measurement area or when a periodic RNA updatefails, the validity timer is stopped or reset.

A detailed operation of the first measurement operation may be specifiedas follows. The UE may measure RSRP/RSRQ of a synchronization signalblock (SSB) of a serving cell/frequency according to a DRX period. Whenmeasuring a non-serving frequency, the UE may measure an SSB of thefrequency indicated by the NR-ARFCN. The UE may measure the servingfrequency in every DRX and the non-serving frequency in every n*DRXperiod. The integer n may be indicated through an RRC message or systeminformation. Even though the measurement result of the serving frequencyis greater than SnonIntraSearchP and SnonIntraSearchQ indicated bysystem information (for example, Srxlev>S_(nonIntraSearchP) orSqual>S_(nonIntraSearchQ)), the UE may measure the non-servingfrequency.

If the first condition is not satisfied, the UE performs a secondmeasurement operation. For example, the UE may perform the secondmeasurement operation if the validity timer is not being driven. Adetailed operation of the second measurement operation may be specifiedas follows. The UE may measure RSRQ/RSRQ of an SSB of a servingcell/frequency according to a DRX period. Measurement of a frequencyhaving a higher priority than the serving frequency among non-servingfrequencies of SIB 5 may be performed in every DRX period. Measurementof a frequency having a lower priority than (or equal to) the servingfrequency among non-serving frequencies of SIB 5 may be performed inevery DRX period if a predetermined condition is satisfied. For example,the predetermined condition may be satisfied when the measurement resultof the serving frequency is lower than S_(nonIntraSearchP) andS_(nonIntraSearchQ) indicated by system information.

When an RRC connection resume procedure is initiated, the UE may performthe following procedure. The UE may perform a random access procedure.The UE may insert information indicating that there is an inactive statemeasurement result into message 3 (Msg 3). For example, the UE mayinform the eNB that there is the inactive state measurement result byinserting a predetermined IE into an LCID of MAC control information oran RRC message (for example, RRCResumeRequest message). When receivinginformation indicating a report of the inactive state measurement resultfrom the eNB through message 4 (Msg 4/RRCResume), the UE may generateand report the inactive state measurement result.

The inactive state measurement report message of step 855 may includethe measurement result. In an embodiment, the measurement result mayinclude a serving cell measurement result. For example, the serving cellmeasurement result may include L3-filtered RSRP/RSRQ. The measurementresult may include an inter-frequency measurement result. The UE mayreport the measurement result for one cell having the highest RSRP orRSRQ among valid measurement results for each frequency. For example,the inter-frequency measurement result may include at least one of anNR-ARFCN, a physical cell identifier (PCI), L3 filtered RSRP/RWRQ, and atime passed from measurement.

The disclosure provides a method of defining a state of the UE for theSCell configured in the UE as an activated state, a deactivated state,or a dormant state, defining an operation of the UE in each state, andswitching the state through MAC control information. Accordingly, thedisclosure provides an apparatus and a method by which the UE may morerapidly perform frequency measurement and more rapidly report thefrequency measurement result to the eNB, and thus the eNB may morerapidly configure carrier aggregation technology.

In order to support a service having a higher data transmission rate anda lower transmission delay in the next-generation mobile communicationsystem (for example, the NR communication system), the eNB may berequired to rapidly configure frequency aggregation (CA) technology ordual connectivity (DC) technology in the UE. However, a frequencymeasurement result of the UE is needed to configure the technology inthe UE. It is required to define the state of the UE for the SCellconfigured in the UE and configure or control the UE to perform “fastfrequency measurement” and report the measurement result.

The states of the UE which the eNB configures in the UE for eachSecondary cell (SCell) are defined as an activated state, a deactivatedstate, and a dormant state, and operations of the UE in each state willbe described.

A transition method between three states for each SCell using new MACcontrol information is described below. For example, in the dormantstate, as the UE rapidly perform frequency measurement and rapidlyreports the frequency measurement report to the eNB, the eNB may rapidlyconfigure carrier aggregation technology. Further, by controlling thestate of the UE for each SCell which the eNB configures in the UE usingMAC control information, the SCell may be dynamically controlled.Accordingly, the eNB may rapidly serve a greater amount of data to theUE with smaller signaling overhead and lower transmission delay throughCA or DC.

The disclosure provides methods of introducing a new dormant state forallowing the UE to perform frequency measurement and report themeasurement result even though the UE is not activated for each SCelland switching the states. The methods may be very useful when thenetwork rapidly configures CA or DC in the UE in an environment in whichsmall cells are deployed in a macro cell.

FIG. 9 is a flowchart of a method for configuring an SCell by the UE ina wireless communication system according to an embodiment. The UEcorresponds to the UE 135 of FIG. 1 or the UE 315 of FIG. 3. The UEreceives frequency measurement configuration and state configuration forSCells, performs state transition according to an indication of MACcontrol information, and performs an operation according to theconfigured state in the next-generation mobile communication system,that is, the NR system.

Referring to FIG. 9, in step 901, the UE may identify SCellconfiguration information. The UE may receive frequency measurementconfiguration information from at least one of system information, anRRC message for switching the mode of the UE (for example, an RRCinactive mode or an RRC idle mode) or a message received in RRCconnection configuration. Frequency measurement information may includeSCell configuration information. The UE may identify SCell configurationinformation.

The SCell configuration information may indicate an initial state ofeach SCell.

In step 903, the UE may operate according to the initial stateconfigured in each SCell. The SCell configuration information mayindicate an initial state of each SCell. The UE may configure theinitial state of each SCell. The UE may identify the initial stateconfigured in each SCell and operate according to the identified state.The initial state may be one of an activated state, a deactivated state,and a dormant state. The UE may measure a serving cell based on theinitial state configured in the corresponding SCell.

In step 905, the UE may receive transition information. The transitioninformation may be information indicating transition of the state of theSCell of the UE to another state. The transition information may switchthe SCell from a particular state to another particular state. A statefrom which the SCell transitions and a state to which the SCelltransitions may be indicated by the type of transition information or avalue of transition information. For example, the transition informationmay indicate transition from an activated state to a dormant state. Forexample, the transition information may indicate transition from anactivated state to a deactivated state. For example, the transitioninformation may indicate transition from a deactivated state to adormant state. For example, the transition information may indicatetransition from a deactivated state to an activated state. For example,the transition information may indicate transition from a dormant stateto an activated state. For example the transition information mayindicate transition from a dormant state to a deactivated state. Thetransition information may be a MAC CE. The MAC CE is described below ingreater detail with reference to FIGS. 12A, 12B, 13A, 13B, 13C, 14A,14B, 15A, 15B, 16A, 16B, 17A, 17B, 18A, and 18B.

In step 907, the UE may switch the state of the SCell. The UE may switchthe state of the SCell based on the transition information, for example,the MAC CE received in step 905. For example, the UE may switch a firstSCell from the activated state to the dormant state. For example, the UEmay switch the first SCell from the activated state to the deactivatedstate. For example, the UE may switch a second SCell from thedeactivated state to the dormant state. For example, the UE may switchthe second SCell from the deactivated state to the activated state. Forexample, the UE may switch a third SCell from the dormant state to theactivated state. For example, the UE may switch the third SCell from thedormant state to the deactivated state.

In step 909, the UE may operate according to the transitioned state. TheUE may measure the corresponding SCell based on the transitioned stateof the SCell. For example, when the SCell transitions to the activatedstate, the UE may measure the SCell in every DRX period. For example,when the SCell transitions to the deactivated state, the UE may measurethe SCell in every DRX period or every SCell measurement periodseparated configured. For example, when the SCell transitions to thedormant state, the UE may measurement the SCell and report themeasurement result.

FIG. 10 is a flow diagram of signaling between an eNB and a UE forconfiguring an SCell in a wireless communication system according to anembodiment. The UE corresponds to the UE 135 of FIG. 1 or the UE 315 ofFIG. 3. The eNB corresponds to the eNB 110 of FIG. 1, the gNB 310, orthe eNB 315 of FIG. 3.

Referring to FIG. 10, the UE is in the RRC-connected mode in step 1005.When there is no data transmission and reception of the UE, whichtransmits and receives data in the RRC-connected mode, for apredetermined reason or for a predetermined time, the eNB may transmitan RRC message (for example, RRC connection release, RRC connectionsuspend, or a new RRC message) to the UE and control the UE totransition to the RRC idle mode or the RRC inactive mode in step 1010.That is, when the UE in the RRC-connected mode transitions to the RRCidle mode or the RRC inactive mode, the network may transmit the RRCmessage to instruct the UE to switch the mode.

According to an embodiment, by defining the indicator in the RRC messagewhen making the UE transition to the RRC idle mode or the RRC inactivemode through the RRC message, the eNB may indicate to the UE whether tostore and maintain or discard configuration information of SCells orSCell status (active status, idle status, or inactive status)information in the RRC idle mode or the RRC inactive mode. If mobilityof the UE is not great, the configuration information may be directlyreused.

In step 1015, the UE transitions to the RRC idle mode or the RRCinactive mode according to the indication of the RRC message. In the RRCidle mode or the RRC inactive mode, the UE may perform cell reselectionduring movement.

In step 1020, the UE may receive system information of the cell. The UEsearches for a suitable cell based on cell reselection. When a cell onwhich the UE camps is found, the UE receives and reads systeminformation of the cell in step 1020.

The UE may camp on the cell in the RRC idle mode or the RRC inactivemode and read information on a frequency to be measured, a priority ofthe frequency, and timer information from the system information of thecorresponding cell (for example, SIB 5 in the LTE system and SIB 1, SIB2, SIB 3, SIB 4, or SIB 5 in the NR system).

At least one piece of the information included in the RRC messagedescribed in step 1010 may be broadcasted as system information of step1020. The UE in the RRC idle mode or the RRC inactive mode may performfrequency measurement according to frequency measurement informationconfigured as the RRC message or frequency measurement informationconfigured as system information.

In step 1030, the UE may transmit a RAP. The eNB may receive a randomaccess preamble. In step 1035, the eNB may transmit a RAR in response tothe RAP. The UE may receive the RAR.

Subsequently, the UE which does not currently configure the connection,that is, the UE in the RRC idle mode or the RRC inactive mode mayperform an RRC connection establishment process with the eNB when datato be transmitted is generated. The UE may establish forwardtransmission synchronization with the eNB through the random accessprocess in steps 1030 and 1040.

In step 1040, the UE may transmit an RRCConnectionRequest message to theeNB. The message includes a reason (establishmentCause) to establish theconnection with an identifier of the UE. In step 1045, the eNB maytransmit an RRCConnectionSetup message to allow the UE to establish theRRC connection. The message may include RRC connection configurationinformation. The RRC connection may be referred to as an SRB and is usedfor transmission and reception of the RRC message which is a controlmessage between the UE and the eNB. The UE establishing the RRCconnection transmits an RRCConnetionSetupComplete message to the eNB instep 1050.

The RRCConnetionSetupComplete message is included in a control message(for example, a service request) making a request by the UE forestablishing a bearer for a predetermined service to the MME. The eNBmay transmit the control message included in theRRCConnetionSetupComplete message to the MME. The MME determines whetherto provide the service requested by the UE. If it is determined toprovide the service requested by the UE based on the determinationresult, the MME transmits a setup request message (for example, aninitial context setup request) to the eNB. The setup request message mayinclude QoS information to be applied to establishment of the DRB andsecurity-related information to be applied to the DRB (for example, asecurity key and a security algorithm). The eNB may transmit a securityconfiguration message (for example, SecurityModeCommand) to configuresecurity with the UE in step 1055 and transmit a security configurationcompletion message (for example, SecurityModeComplete) to inform the eNBof security configuration in step 1060, which completes the securityconfiguration procedure.

In step 1070, the eNB may transmit an RRCConnectionReconfigurationmessage to the UE. When security configuration is completed in steps1055 and 1060, the eNB may transmit an RRCConnectionReconfigurationmessage to the UE. The message may include configuration information ofthe DRB for processing user data.

In step 1075, the UE may transmit anRRCConnectionReconfigurationComplete message to the eNB. The UE mayestablish the DRB by applying the configuration information of the DRBreceived in step 1070 and transmit theRRCConnectionReconfigurationComplete message to the eNB.

According to an embodiment, a common configuration parameter or aconfiguration parameter for each SCell may be introduced to efficientlyperform configuration for a plurality of SCells through the RRC message(RRC connection reconfiguration of step 1070). The eNB or the UE may usethe common configuration parameters or the configuration parameter foreach of the SCells. When the common configuration parameter and theconfiguration parameter for each SCell are configured, the configurationfor each SCell may have precedence over the common configurationparameter. For example, a group identifier is defined and then a mappingrelation with each SCell identifier may be defined. That is, one groupidentifier may be mapped to each of all SCell identifiers and one groupidentifier may indicate common configuration information of all SCells.Further, a plurality of group identifiers may be defined and SCellidentifiers mapped to respective group identifiers may be defined, sothat configuration information of cells may be configured in groupunits. The RRC message may include mapping information with a bandwidthpart ID indicating a bandwidth part to be used for the SCell based onthe SCell identifier, time/frequency resource information, or bandwidthpart configuration information corresponding to each SCell.

The eNB completing establishment of the DRB with the UE transmits aninitial context setup complete message to the MME. The MME receiving themessage exchanges an S1 bearer setup message and an S1 bearer setupresponse message with the S-GW in order to establish the S1 bearer. TheS1 bearer is a connection for data transmission established between theS-GW and the eNB and corresponds to the DRB in one-to-onecorrespondence. When the processor is completed, the UE transmits andreceives data through the eNB and the S-GW. Further, the eNB maytransmit an RRC Connection Reconfiguration message in order to providenew configuration to the UE or add or change the configuration for apredetermined reason.

The UE may perform frequency measurement. The UE may perform frequencymeasurement for each of the configured SCells based on the receivedfrequency measurement configuration information. The UE may performfrequency measurement according to the state of the UE for each of theconfigured SCells (activated state, dormant state, or deactivatedstate).

The eNB may report the frequency measurement result to the UE throughvarious methods. In an embodiment, the UE may report the frequencymeasurement result to the eNB in step 1080. The eNB may report frequencymeasurement results satisfying a predetermined condition to the eNB. Ifthere is a valid frequency measurement result when providing the reportto the eNB, the UE may directly provide the report to the eNB through anRRC message or MAC control message or periodically provide the report.The UE may report the frequency measurement result only when there is arequest for the frequency measurement information in step 1085. The UEmay report the frequency measurement result to the eNB based on anindicator indicating the existence of the valid frequency measurementresult. For example, the UE may transmit the indicator indicating theexistence of the valid frequency measurement result to the eNB. The eNBmay make a request for the frequency measurement result to the UE asnecessary. Thereafter, the eNB may receive the frequency measurementresult.

When the SCells are configured through the RRC message, an initial stateof each SCell may be configured as an activated state, a dormant state,or a deactivated state. When the SCells are configured to have theinitial state which is the activated state or the dormant stateaccording to configuration information of the SCells, the UE maydirectly perform report frequency measurement for the SCells, so thatthe eNB may rapidly apply CA.

The activated state, the dormant state, or the deactivated state of eachSCell may be indicated by transmitting MAC control information to theUE. In addition, switching between RRC modes may be indicated bytransmitting MAC control information to the UE.

When the SCell is in the activated state or the dormant state, the UE inthe RRC-connected mode may perform frequency measurement and report thefrequency measurement result to the eNB. The frequency measurementreport may be provided through an RRC message or MAC controlinformation. When the state of each SCell is configured as the activatedstate or the dormant state through the RRC message, the UE may beconfigured based on frequency measurement configuration informationincluding an integer indicating when PDCCH monitoring is started andwhen the report of the frequency (channel or cell) measurement result isstarted. For example, the UE may start the measurement report after timeunits (for example, subframes, time slots, or TTIs) corresponding to theindicated integer.

When the initial states of the SCells are configured using the RRCmessage, the eNB may define an indicator of the RRC message to rapidlyapply CA and configure the initial state of each SCell as the activatedstate or the dormant state. If fast CA (CA configured according to fastfrequency measurement) is not necessary, the initial state may beconfigured as the deactivated state. The eNB may configure a timer valuein the RRC message, and when the timer value expires, configure the UEto automatically switch the state of the SCell from the activated stateto the dormant state, or when the timer value expires, configure the UEto automatically switch the state of the SCell from the dormant state tothe deactivated state, or when the timer value expires, configure the UEto automatically switch the state of the SCell from the activated stateto the deactivated state, thereby saving battery power and reducesignaling overhead. The configuration of the SCells may be performed ininitial connection configuration or in handover or performed as the eNBtransmits the RRC message to the UE in the RRC-connected mode.

According to an embodiment, frequency measurement performed by the UE inthe dormant state for the SCell may be different from frequencymeasurement performed in the activated state for the SCell. That is,while frequency measurement for the SCell performed in the activatedstate is possible based on a CSI-RS based on a time reference value ofthe Pcell of the current UE, frequency measurement in the dormant statemay be difficult based on the CSI-RS. Accordingly, the UE may measureRSRP, RSRQ, and RS-SINR based on a CRS. Therefore, reference signalswhich are objects for measuring the frequency may be different in theactivated state and the other state (for example, the dormant state).

As described above, the UE may initiate frequency measurement at varioustime points. That is, a time point at which frequency measurement startsmay be one of the following time points.

The UE may start frequency measurement at a time point at which the UEreceives the RRC message of step 1010 and reads frequency measurementconfiguration information.

The UE may receive the RRC message of step 1010, read frequencymeasurement configuration information, and start frequency measurementafter n time units (for example, subframes, time slots, or TTIs)indicated (or pre-appointed) by the frequency measurement configurationinformation.

The UE may receive the RRC message of step 1010, read frequencymeasurement configuration information, and start frequency measurementafter n time units (for example, subframes, time slots, or TTIs)indicated when the state of the UE for each SCell indicated (orpre-appointed) by the frequency measurement configuration information isconfigured and the configured state is the activated state or thedormant state.

The UE may receive the RRC message of step 1010, read frequencymeasurement configuration information, and start frequency measurementwhen the state of the UE for each SCell indicated (or pre-appointed) bythe frequency measurement configuration information is configured andthe configured state is the activated state or the dormant state.

The UE may transmit a necessary frequency measurement result among allfrequency measurement results to the network (eNB). According to anembodiment, the UE performing the frequency measurement in the RRC idlemode or the RRC inactive mode may report the frequency measurementresult for carriers (SCell), to which CA can be applied, to the network.The UE may report the measurement result only for the SCell satisfying apredetermined condition. In other words, the SCell to which CA can beapplied is the SCell satisfying the predetermined condition.

The UE may report the frequency measurement report for the SCellsatisfying the predetermined condition to the network based onmeasurement of the UE. If a period is given, the UE may performmeasurement in every corresponding period. The predetermined conditionmay include at least one of the following conditions.

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value is maintained for a predetermined time, the condition issatisfied (the threshold value and the time may be configured in the UEthrough an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value is measured a predetermined number of times or more, thecondition is satisfied (the threshold value and the number of times maybe configured in the UE through an RRC message or may be broadcastedthrough system information).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a predetermined time is measured a predeterminednumber of times or more, the condition is satisfied (the thresholdvalue, the time, and the number of times may be configured in the UEthrough an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a first time (for example, while a timer isdriven) is maintained for a second time, the condition is satisfied (thethreshold value, the first time, and the second time may be configuredin the UE through an RRC message or may be broadcasted through systeminformation).

When a state in which the intensity of the signal of the frequency (forexample, RSRP, RSRQ, or RS-SINR) is greater than a predeterminedthreshold value within a first time (for example, while a timer isdriven) is measured a predetermined number of times or more, thecondition is satisfied (the threshold value, the first time, and thenumber of times may be configured in the UE through an RRC message ormay be broadcasted through system information).

When the frequency measured by the UE in the RRC idle mode or the RRCinactive mode is a cell or a frequency indicated by system informationof the serving cell which the UE accesses, the condition is satisfied CAtechnology can be supported for a plurality of cells served by one eNB,so that the CA technology cannot be applied no matter how good is asignal of a cell served by another eNB. Accordingly, the frequencymeasurement result can be used for application of the CA technology onlywhen the frequency measurement result is a measurement result for thecell which the UE accesses or the frequency supported by the eNB). Forexample, when the frequency is a frequency or a cell belonging to a celllist indicated by system information (white cell list), thecorresponding frequency or cell satisfies the condition.

When the eNB does not know UE capability of the UE currently having theestablished connection or when the eNB is required to identify UEcapability, the eNB may transmit a message (for example, a UE capabilityinquiry) asking of UE capability. The UE may transmit a message (forexample, UE capability) reporting its own capability. Through themessage, the UE may report information on whether frequency measurementcan be performed in the RRC idle mode or the RRC inactive mode orinformation on frequencies or a frequency area which can be measured ora maximum number of frequencies which can be measured to the eNB.

When the state of the SCells configured in the UE is the activated stateor the dormant state, when the UE performs handover or radio linkfailure (RLF) is generated, or when the Pcell is changed, the state ofthe SCells may transition to the deactivated state in order to preventunnecessary PDCCH monitoring and frequency measurement. That is, the UEmay fall back the state of each SCell. That is, the UE may performimplicit state transition.

For the SCell configured as the activated state, the UE monitor a PDCCHto monitor a signal of the eNB, perform channel quality indicator (CQI)or radio resource monitoring (RRM) measurement according to RRCconfiguration, and when the DRX is configured, perform CQI or RRMmeasurement according to the DRX, and report the measurement result tothe eNB. The frequency measurement result report may be provided fromthe UE to the eNB through the RRC message, or MAC control informationmay be defined and then the frequency measurement report may be providedthrough the MAC control information.

For the SCell configured as the dormant state, the UE may performfrequency measurement (CQI or RRM measurement) according to the DRX ofthe Pcell and trigger the frequency measurement report so as to providethe report to the eNB. That is, the UE may perform frequency measurementin an on-duration interval in which the UE should turn on the RF tomonitor the PDCCH in the DRX of the Pcell. The frequency measurementresult report may be provided from the UE to the eNB through the RRCmessage. Alternatively, MAC control information may be defined and theUE may report the frequency measurement result through the MAC controlinformation. In order to save battery power, PDCCH monitoring formonitoring the indication of the eNB may not be performed.

For the SCell configured as the dormant state, the UE may not performPDCCH monitoring for monitoring the indication of the network in orderto save battery power. The UE may provide a periodic frequencymeasurement (channel measurement) report in order to rapidly supportactivation of the SCell. The frequency measurement (channel measurement)report may be provided based on the CRS.

For the SCell configured as the deactivated state, the UE may notmonitor the signal of the eNB. That is, not monitor the PDCCH andperform frequency measurement (RRM), but not report the measurementresult to the eNB. In the deactivated state, the frequency measurementmay be performed according to an SCell measurement report periodconfigured through RRC.

FIG. 11 is an illustration of a state transition of an SCell accordingto an embodiment. A UE may maintain a particular state for the SCell ortransition to another particular state. The state for the SCell may bean activated state, a dormant state, or a deactivated state. That is,the UE may maintain the activated state, the dormant state, or thedeactivated state for each SCell or perform state transition based onMAC control information. Hereinafter, the activated state may bereferred to as Ac, the dormant state may be referred to as Do, and thedeactivated state may be referred to as De, and thus the statetransition for the SCell is described below. The state transition mayinclude cases 1105, 1110, and 1115 in which the state which is the sameas a previous state is maintained.

Referring to FIG. 11, nine state transitions below may be possible.

1105: Ac to Ac (maintain the state)

1110: Do to Do (maintain the state)

1115: De to De (maintain the state)

1120: Ac to Do (used for saving battery power of the UE and easilyperforming scheduling)

1125: Do to AC (used for activating CA)

1130: De to Do (used for receiving a frequency measurement report beforeactivating CA)

1135: Do to De (used for preventing and deactivating a frequencymeasurement report in order to save battery power of the UE)

1140: De to AC (used for activating CA)

1145: Ac to De (used for saving battery power of the UE and easilyperforming scheduling)

According to an embodiment, a particular state transition may not beused. The state transition 1130 (De to Do) may not be supported if thefrequency or the usage of use cases thereof is low. Whether to use theparticular state transition is adaptively configurable. Hereinafter,detailed embodiments of MAC control information for supporting statetransitions of the disclosure described in FIG. 11 is described belowwith reference to FIGS. 12A, 12B, 13A, 13B, 13C, 14A, 14B, 15A, 15B,16A, 16B, 17A, 17B, 18A, and 18B. With reference to FIGS. 12A to 18B,roles of each MAC CE are described below. Each MAC CE may be identifiedby a MAC PDU and an LCID.

FIGS. 12A and 12B are illustrations of a first embodiment of MAC controlinformation supporting a state transition for an SCell in a wirelesscommunication system according to an embodiment. The first embodiment ofthe MAC control information is described below with reference to FIG.11. The first embodiment of the MAC control information illustrated inFIG. 12A does not support the state transition 1130 (De to Do) of FIG.11. As described above, the state transition 1130 (De to Do) may not besupported because the frequency or the usage of use cases thereof may below.

Referring to FIGS. 12A and 12B, a first MAC CE and a second MAC CE aredefined as MAC control information, and state transition according tothe first MAC CE or the second MAC CE is supported. The first MAC CE candeactivate the SCell which is in the dormant state but cannot activatethe SCell. The second MAC CE cannot switch the state of the SCell whichis in the deactivated state.

First MAC control information, that is, the first MAC CE according tothe first embodiment is described below. The first MAC CE may bereferred to as an activation/deactivation MAC CE. The first MAC CE mayhave the fixed size of 1 byte and may be identified by a logical channelidentifier (LCID). The first MAC CE may have one reserved (R) field anda detailed format thereof is the same as that of an MAC CE 1211 of FIG.12B. The MAC CE 1211 consists of one octet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1213 of FIG. 12B. The MAC CE 1213 consists of four octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell corresponding to a cell ID i is inan activated state, a deactivated state, or a dormant (hibernation)state if there is an SCell configured with SCellIndex i. Otherwise, aMAC layer device (for example, a MAC entity) ignores this field. Whenthe C(i) field is set to 1, the C(i) field indicates that the state ofthe SCell configured with SCellIndex i should be activated. However,when the state of the SCell configured with SCellIndex i is the dormantstate, the MAC entity ignores the value of 1 of the C(i) field. When theC(i) field is set to 0, the C(i) field indicates that the state of theSCell configured with SCellIndex i is deactivated.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the first embodiment may be defined asshown in Table 1 below.

TABLE 1 C(i) field State transition 0 Ac→De, Do→De, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in the firstembodiment is described below. The second MAC CE may be referred to asan activation/hibernation MAC CE.

The second MAC CE may have the fixed size of 1 byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of the MAC CE1221 of FIG. 12B. The format is the same as that of the MAC CE 1221. TheMAC CE 1221 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of the MAC CE1223 of FIG. 12B. The MAC CE 1223 consists of four octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates thatthe state for the SCell configured with SCellIndex i should beactivated. However, when the SCell configured with SCellIndex i is inthe deactivated state, the MAC entity ignores the one value (0 or 1, forexample, 1) of the 1-bit information. When the C(i) field is set to onevalue (0 or 1, for example, 0) of 1-bit information, the C(i) fieldindicates that the state for the SCell configured with SCellIndex ishall be dormant. However, when the SCell configured with SCellIndex iis in the deactivated state, the MAC entity ignores the one value (0 or1, for example, 1) of the 1-bit information.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the first embodiment maybe defined as shown in Table 2 below.

TABLE 2 C(i) field State transition 0 Ac→Do, Do→Do, De→De 1 Ac→Ac,Do→Ac, De→De

In the first MAC CE and the second MAC CE according to the firstembodiment, MAC CE having the size of 1 byte and MAC CEs having the sizeof 4 bytes may have different logical channel identifiers and thus maybe distinguished from each other. Further, the first MAC CE and thesecond MAC CE may have fixed lengths. In this case, a length (L) fieldis not needed in a MAC sub header.

In another method, the R field may be used for saving a space of theLCID. LCID 1 indicates the first MAC CE or the second MAC CE having thesize of 1 byte, and may indicate the first MAC CE having the size of 1byte if the R field value is 0 and indicate the second MAC CE having thesize of 1 byte if the R field value is 1. LCID 2 indicates the first MACCE or the second MAC CE having the size of 4 bytes, and may indicate thefirst MAC CE having the size of 4 bytes if the R field value is 0 andindicate the second MAC CE having the size of 4 bytes if the R fieldvalue is 1. Accordingly, in this case, an L field is not needed in a MACsub header.

MAC control information indicating the state transition of thedisclosure should support all state transition for each cell of FIG. 11.An example of how the first MAC CE and the second MAC CE in the firstembodiment support the state transition of each SCell is describedbelow. When there is a plurality of states for each SCell as shown inTable 3 below, it may be identified that MAC control information iscorrectly designed through a change in only one state to another state.The first MAC CE and the second MAC CE in the first embodiment supportstate transitions for the number of all cases as shown in Table 3 below.

TABLE 3 SCell index 7 6 5 4 3 2 1 State Ac Ac Ac De De Do Do MAC CE 1 01 1 0 0 1 1 State De Ac Ac De De Do Do MAC CE 2 0 0 1 0 0 0 0 State DeDo Ac De De Do Do MAC CE 1 0 1 1 1 0 1 1 State De Do Ac Ac De Do Do MACCE 1 0 0 1 1 0 1 1 State De De Ac Ac De Do Do MAC CE 2 0 0 1 1 0 1 0State De De Ac Ac De Ac Do

FIGS. 13A, 13B, and 13C are illustrations of a second embodiment of MACcontrol information supporting state transition for the SCell in awireless communication system according to an embodiment. The secondembodiment of the MAC control information is described below withreference to FIG. 11. The second embodiment of the MAC controlinformation supports the state transition 1130 (De to Do) of FIG. 11.That is, even though the frequency or the usage of use cases of thestate transition 1130 (De to Do) is low, it is possible to save batterypower of the UE and report a frequency measurement result in advance byswitching the SCell in the deactivated state to the dormant state. TheeNB may determine whether to perform activation according to thereported frequency measurement result and thus the state transition 1130may be useful.

Referring to FIGS. 13A, 13B, and 13C, a first MAC CE and a second MAC CEare defined as the MAC control information, and state transitionaccording to the first MAC CE or the second MAC CE is supported. Thefirst MAC CE can deactivate the SCell which is in the dormant state butcannot activate the SCell which is in the dormant state. Further, thesecond MA CE may switch the SCell in the deactivated state to thedormant state through one value (0 or 1, for example, 1) of 1-bitinformation and continuously maintain the deactivated state of the SCellwhich is in the deactivated state through one value (0 or 1, forexample, 0) of 1-bit information.

First MAC control information, that is, the first MAC CE in the secondembodiment is described below. The first MAC CE may be referred to as anactivation/deactivation MAC CE. The first MAC CE may have the fixed sizeof one byte and may be identified by an LCID. The first MAC CE may haveseven C fields and one R field and a detailed format thereof is the sameas that of an MAC CE 1311 of FIG. 13B. The MAC control information 1311consists of one octet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1313 of FIG. 13B. The MAC CE 1313 consists of four octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to 1, the C(i)field indicates that the state of the SCell configured with SCellIndex ishould be activated. However, when the state of the SCell configuredwith SCellIndex i is the dormant state, the MAC entity ignores the valueof 1 of the C(i) field. When the C(i) field is set to 0, the C(i) fieldindicates that the state of the SCell configured with SCellIndex i isdeactivated.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the first embodiment may be defined asshown in Table 4 below.

TABLE 4 C(i) field State transition 0 Ac→De, Do→De, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in the secondembodiment is described below. The second MAC CE may be referred to asan activation/hibernation MAC CE.

The second MAC CE may have the fixed size of one byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1321 of FIG. 13B. The format is the same as that of the MAC CE 1321. TheMAC CE 1321 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1323 of FIG. 13B. The MAC CE 1323 consists of four octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates thatthe state for the SCell configured with SCellIndex i should beactivated. However, when the state of the SCell configured withSCellIndex i is the deactivated state, one value (0 or 1, forexample, 1) of 1-bit information of the C(i) field indicates statetransition of the SCell to the dormant state. When the C(i) field is setto one value (0 or 1, for example, 0) of 1-bit information, the C(i)field indicates that the state for the SCell configured with SCellIndexi shall be dormant. However, when the SCell configured with SCellIndex iis in the deactivated state, the MAC entity ignores the one value (0 or1, for example, 1) of the 1-bit information.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the second embodimentmay be defined as shown in Table 5 below.

TABLE 5 C(i) field State transition 0 Ac→Do, Do→Do, De→De 1 Ac→Ac,Do→Ac, De→Do

In the second embodiment, the second MAC CE according to anotherembodiment may be configured to be the same as the design methoddescribed above. Alternatively, another second MAC CE may be designedsuch that the meanings indicated by bit values (0 and 1) of each bithaving 0 or 1 are exchanged.

The second MAC CE may have the fixed size of one byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1331 of FIG. 13C.

Further, the second MAC CE may have the fixed size of four bytes and maybe identified by an LCID. The second MAC CE may have 31 C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1333 of FIG. 13C.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 0) of 1-bit information, the C(i) field indicates thatthe state for the SCell configured with SCellIndex i should beactivated. However, when the SCell configured with SCellIndex i is inthe deactivated state, the MAC entity ignores the one value (0 or 1, forexample, 1) of the 1-bit information. When the C(i) field is set to onevalue (0 or 1, for example, 1) of 1-bit information, the C(i) fieldindicates that the state for the SCell configured with SCellIndex ishould be the dormant state.

R field: denotes a reserved field and is configured as 0.

TABLE 5-1 C(i) field State transition 0 Ac→Ac, Do→Ac, De→De 1 Ac→Do,Do→Do, De→Do

In the first MAC CE and the second MAC CE according to the secondembodiment, MAC CE having the size of 2 byte and MAC CEs having the sizeof 4 bytes may have different logical channel identifiers and thus aredistinguished from each other. Further, the first MAC CE and the secondMAC CE may have fixed lengths. Accordingly, in this case, an L field isnot needed in a MAC sub header.

In another method, the R field may be used for saving a space of theLCID. That is, LCID 1 indicates the first MAC CE or the second MAC CEhaving the size of 1 byte, and may indicate the first MAC CE having thesize of 1 byte if the R field value is 0 and indicate the second MAC CEhaving the size of 1 byte if the R field value is 1. LCID 2 indicatesthe first MAC CE or the second MAC CE having the size of 4 bytes, andmay indicate the first MAC CE having the size of 4 bytes if the R fieldvalue is 0 and indicate the second MAC CE having the size of 4 bytes ifthe R field value is 1. Accordingly, in this case, an L field is notneeded in a MAC sub header.

MAC control information indicating the state transmission of thedisclosure should support all state transmissions for each SCell of FIG.11. An example of how the first MAC CE and the second MAC CE in thefirst embodiment support the state transition of each SCell is describedbelow.

When there is a plurality of states for each SCell as shown in Table 6below, it may be identified that MAC control information is correctlydesigned through a change in only one state to another state. The firstMAC CE and the second MAC CE in the second embodiment support statetransitions for the number of all cases as shown in Table 6 below.

TABLE 6 SCell index 7 6 5 4 3 2 1 State Ac Ac Ac De De Do Do MAC CE 1 01 1 0 0 1 1 State De Ac Ac De De Do Do MAC CE 2 0 0 1 0 0 0 0 State DeDo Ac De De Do Do MAC CE 1 0 1 1 1 0 1 1 State De Do Ac Ac De Do Do MACCE 1 0 0 1 1 0 1 1 State De De Ac Ac De Do Do MAC CE 2 0 0 1 1 0 1 0State De De Ac Ac De Ac Do MAC CE 2 1 0 1 1 0 1 0 State Do De Ac Ac DeAc Do

FIGS. 14A and 14B are illustrations of a third embodiment of MAC controlinformation supporting state transition for the SCell in a wirelesscommunication system according to an embodiment. The third embodiment ofthe MAC control information is described below with reference to FIG.11. The third embodiment of the MAC control information supports thestate transition 1130 (De to Do) of FIG. 11. That is, even though thefrequency or the usage of use cases of the state transition 1130 (De toDo) is low, it is possible to save battery power of the UE and report afrequency measurement result in advance by switching the SCell in thedeactivated state to the dormant state. The eNB may determine whether toperform activation according to the reported frequency measurementresult and thus the state transition 1130 may be used.

Referring to FIGS. 14A and 14B, a first MAC CE and a second MAC CE aredefined as the MAC control information, and state transition accordingto the first MAC CE or the second MAC CE is supported. The first MAC CEcannot switch the state of the SCell which is in the dormant state. Thesecond MAC CE may indicate each of all states for each SCell through 2bits or initialize the states to a particular state. Accordingly, if thesecond MAC CE is used, the eNB does not need to track the statetransition for each SCell of the UE. Therefore, complexity ofimplantation of the eNB may be reduced.

First MAC control information, that is, the first MAC CE in the thirdembodiment is described below. The first MAC CE may be referred to as anactivation/deactivation MAC CE. The first MAC CE may have the fixed sizeof one byte and may be identified by an LCID. The first MAC CE may haveseven C fields and one R field and a detailed format thereof is the sameas that of an MAC CE 1411 of FIG. 14B. The MAC CE 1411 consists of oneoctet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1413 of FIG. 14B. The MAC CE 1413 consists of four octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the deactivated state, or the dormant state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to 1, the C(i)field indicates that the state of the SCell configured with SCellIndex ishould be activated. However, when the state of the SCell configuredwith SCellIndex i is the dormant state, the MAC entity ignores the C(i)field. When the C(i) field is set to 0, the C(i) field indicates thatthe state of the SCell configured with SCellIndex i is deactivated.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the third embodiment may be defined asshown in Table 7 below.

TABLE 7 C(i) field State transition 0 Ac→De, Do→Do, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in the thirdembodiment is described below. The second MAC CE may be referred to asan activation/hibernation MAC CE.

The second MAC CE may have the fixed size of 2 bytes and may beidentified by an LCID. The second MAC CE may have seven C fields havingthe size of 2 bits and one R field having the size of 2 bits and adetailed format thereof is the same as that of an MAC CE 1421 of FIG.14B. The MAC CE 1421 consists of two octets.

The second MAC CE may have the fixed size of 8 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields having thesize of 2 bits and one R field having the size of 2 bits and a detailedformat thereof is the same as that of an MAC CE 1423 of FIG. 14B. TheMAC CE 1423 consists of 8 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 2 byte may be used. Otherwise, thesecond MAC CE having the size of 8 bytes may be used.

C(i,1) C(i,0) field: 2-bit information indicating that the SCellconfigured with SCellIndex i is in the activated state, the dormantstate, or the deactivated state if there is an SCell configured withSCellIndex i. Otherwise, the MAC entity ignores this field. When theC(i,1) C(i,0) field is set to one value (00, 01, 10, or 11, for example,00) of 2-bit information, the C(i,1) C(i,0) field may indicate that thestate transition for the SCell configured with SCellIndex i does notoccur or may be a reserved value. When the C(i) field is set to onevalue (00, 01, 10, or 11, for example, 01) of 2-bit information, theC(i,1) C(i,0) field indicates that the state for the SCell configuredwith SCellIndex i should be activated. When the C(i,1) C(i,0) field isset to one value (00, 01, 10, or 11, for example, 10) of 2-bitinformation, the C(i,1) C(i,0) field indicates that the state for theSCell configured with SCellIndex i should be deactivated. When theC(i,1) C(i,0) field is set to one value (00, 01, 10, or 11, for example,11) of 2-bit information, the C(i,1) C(i,0) field indicates that thestate for the SCell configured with SCellIndex i should be dormant.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the third embodiment maybe defined as shown in Table 8 below.

TABLE 8 C(i) field State transition 00 No state transition or reserved01 Activation (activated state) 10 Deactivation (deactivated state) 11Hibernation (dormant state)

When 2 bits are used, the second MAC control information according tothe third embodiment may be defined as shown in Table 9 below in ordernot to support the state transition 1130 (De to Do).

TABLE 9 C(i) field State transition 00 No state transition or reserved01 Ac/Do/De→Ac 10 Ac/Do→Do, De→De 11 Ac/Do/De→De

In the first MAC CE and the second MAC CE according to the thirdembodiment, MAC CEs having the size of 1 byte or 2 bytes and MAC CEshaving the size of 4 bytes or 8 bytes may have different logical channelidentifiers and thus may be distinguished from each other. Further, thefirst MAC CE and the second MAC CE may have fixed lengths. Accordingly,in this case, an L field is not needed in a MAC sub header.

In another method, an L field of a MAC sub header may be used to save aspace of the LCID. That is, LCID 1 may indicate the first MAC CE havingthe size of 1 byte or the second MAC CE having the size of 2 bytes, andmay perform optimization by indicating the first MAC CE having the sizeof 1 byte if the L field value indicates 1 byte and indicating thesecond MAC CE having the size of 2 bytes if the L field value indicates2 bytes LCID 2 may indicate the first MAC CE having the size of 4 bytesor the second MAC CE having the size of 8 bytes, and may performoptimization by indicating the first MAC CE having the size of 4 bytesif the L field value indicates 4 byte and indicating the second MAC CEhaving the size of 8 bytes if the L field value indicates 8 bytesAccordingly, in this case, the L field is not needed in the MAC subheader.

The MAC control information indicating the state transition in thedisclosure should support all state transitions for each SCell of FIG.11. It may be easily identified whether the first MAC CE and the secondMAC CE in the third embodiment of the disclosure support all statetransitions of FIG. 11. It may be intuitively identified whether thethird embodiment supports all state transitions for each SCell of FIG.11 based on the description and tables of FIG. 14A.

FIGS. 15A and 15B are illustrations of a fourth embodiment of MACcontrol information supporting state transition for an SCell in awireless communication system according to an embodiment. The fourthembodiment of the MAC control information is described below withreference to FIG. 11. The fourth embodiment of the MAC controlinformation supports the state transition 1130 (De to Do) of FIG. 11.That is, even though the frequency or the usage of use cases of thestate transition 1130 (De to Do) is low, it is possible to save batterypower of the UE and report a frequency measurement result in advance byswitching the SCell in the deactivated state to the dormant state. TheeNB may determine whether to perform activation according to thereported frequency measurement result and thus the state transition 1130may be used.

Referring to FIGS. 15A and 15B, a first MAC CE and a second MAC CE aredefined as the MAC control information and state transition issupported. The first MAC CE can deactivate the SCell which is in thedormant state but cannot activate the SCell. Further, the second MAC CEmay switch the SCell in the deactivated state to the dormant statethrough one value (0 or 1, for example, 1) of 1-bit information andcontinuously maintain the deactivated state of the SCell which is in thedeactivated state through one value (0 or 1, for example, 0) of 1-bitinformation.

First MAC control information, that is, the first MAC CE in the fourthembodiment is described below. The first MAC CE may be referred to as anactivation/deactivation MAC CE. The first MAC CE may have the fixed sizeof one byte and may be identified by an LCID. The first MAC CE may haveseven C fields and one R field and a detailed format thereof is the sameas that of an MAC CE 1511 of FIG. 15B. The MAC CE 1511 consists of oneoctet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1513 of FIG. 15B. The MAC CE 1513 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to 1, the C(i)field indicates that the state of the SCell configured with SCellIndex ishould be activated. However, when the state of the SCell configuredwith SCellIndex i is the dormant state, the MAC entity ignores the valueof 1 of the C(i) field. When the C(i) field is set to 0, the C(i) fieldindicates that the state of the SCell configured with SCellIndex i isdeactivated.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the fourth embodiment may be defined asshown in Table 10 below.

TABLE 10 C(i) field State transition 0 Ac→De, Do→De, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in the fourthembodiment is described below. The second MAC CE may be referred to asan activation/hibernation MAC CE.

The second MAC CE may have the fixed size of 1 byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1521 of FIG. 15B. The format is the same as that of the MAC CE 1521 ofFIG. 15B. The MAC CE 1521 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1523 of FIG. 15B. The MAC CE 1523 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates thatthe state for the SCell configured with SCellIndex i should beactivated. However, when the state of the SCell configured withSCellIndex i is the deactivated state, one value (0 or 1, for example,0) of 1-bit information of the C(i) field indicates state transition ofthe SCell to the dormant state. When the C(i) field is set to one value(0 or 1, for example, 0) of 1-bit information, the C(i) field indicatesthat the state for the SCell configured with SCellIndex i shall bedormant. However, when the SCell configured with SCellIndex i is in thedeactivated state, the MAC entity ignores the one value (0 or 1, forexample, 1) of the 1-bit information.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the fourth embodimentmay be defined as shown in Table 11 below.

TABLE 11 C(i) field State transition 0 Ac→Do, Do→Do, De→De 1 Ac→Ac,Do→Ac, De→Do

In the first MAC CE and the second MAC CE according to the fourthembodiment, MAC CE having the size of 4 byte and MAC CEs having the sizeof 4 bytes may have different LCIDs and thus are distinguished from eachother. Further, the first MAC CE and the second MAC CE may have fixedlengths. Accordingly, in this case, an L field is not needed in a MACsub header.

In another method, the R field may be used to save a space of the LCID.That is, LCID 1 indicates the first MAC CE or the second MAC CE havingthe size of 1 byte, and may perform optimization by indicating the firstMAC CE having the size of 1 byte if the R field value is 0 andindicating the second MAC CE having the size of 1 byte if the R fieldvalue is 1. LCID 2 indicates the first MAC CE or the second MAC CEhaving the size of 4 byte, and may perform optimization by indicatingthe first MAC CE having the size of 4 byte if the R field value is 0 andindicating the second MAC CE having the size of 4 bytes if the R fieldvalue is 4. Accordingly, in this case, an L field is not needed in a MACsub header.

MAC control information indicating the state transmission of thedisclosure should support all state transmissions for each SCell of FIG.11. An example of how the first MAC CE and the second MAC CE in thefourth embodiment support the state transition is described below.

When there is a plurality of states for each SCell as shown in Table 12below, it may be identified that MAC control information is correctlydesigned through a change in only one state to another state. The firstMAC CE and the second MAC CE in the fourth embodiment of the disclosuresupport the state transition for the number of all cases as shown inTable 12 below.

TABLE 12 SCell index 7 6 5 4 3 2 1 State Ac Ac Ac De De Do Do MAC CE 1 01 1 0 0 1 1 State De Ac Ac De De Do Do MAC CE 2 0 0 1 1 1 1 1 State DeDo Ac De De Do Do MAC CE 1 0 1 1 1 0 1 1 State De Do Ac Ac De Do Do MACCE 1 0 0 1 1 0 1 1 State De De Ac Ac De Do Do MAC CE 2 1 1 1 1 1 1 0State De De Ac Ac De Ac Do MAC CE 2 0 1 1 1 1 1 0 State Do De Ac Ac DeAc Do

FIGS. 16A and 16B are illustrations of a fifth embodiment of MAC controlinformation supporting state transition for an SCell in a wirelesscommunication system according to an embodiment. The fifth embodiment ofthe MAC control information is described below with reference to FIG.11. The fifth embodiment of the MAC control information supports thestate transition 1130 (De to Do) of FIG. 11. That is, even though thefrequency or the usage of use cases of the state transition 1130 (De toDo) is low, it is possible to save battery power of the UE and report afrequency measurement result in advance by switching the SCell in thedeactivated state to the dormant state. The eNB may determine whether toperform activation according to the reported frequency measurementresult and thus the state transition 1130 may be useful.

Referring to FIGS. 16A and 16B, a first MAC CE, a second MAC CE, and athird MAC CE are defined as the MAC control information, and statetransition according to the first MAC CE, the second MAC CE, or thethird MAC CE is supported. The first MAC CE does not perform statetransition for the dormant state of the SCell. The second MAC CEcontinuously maintains the deactivated state for the SCell which is inthe deactivated state through one value (0 or 1, for example, 1) of1-bit information. Further, the second MAC CE does not perform statetransition for the SCell through one value (0 or 1, for example, 0) of1-bit information. The third MAC CE continuously maintains the activatedstate for the SCell which is in the activated state through one value (0or 1, for example, 1) of 1-bit information. Further, the third MAC CEdoes not perform state transition for the SCell through one value (0 or1, for example, 0) of 1-bit information.

First MAC control information, that is, the first MAC CE in the fifthembodiment is described below. The first MAC CE may be referred to as anactivation/deactivation MAC CE. The first MAC CE may have the fixed sizeof 1 byte and may be identified by an LCID. The first MAC CE may haveseven C fields and one R field and a detailed format thereof is the sameas that of an MAC CE 1611 of FIG. 16B. The MAC control information 1611consists of one octet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1613 of FIG. 16B. The MAC CE 1613 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the deactivated state, or the dormant state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to 1, the C(i)field indicates that the state of the SCell configured with SCellIndex ishould be activated. When the C(i) field is set to 0, the C(i) fieldindicates that the state of the SCell configured with SCellIndex i isdeactivated. However, when the state of the SCell configured withSCellIndex i is the dormant state, the MAC entity ignores the C(i)field.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the fifth embodiment may be defined asshown in Table 13 below.

TABLE 13 C(i) field State transition 0 Ac→De, Do→Do, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in the fifthembodiment is described below. The second MAC CE may be referred to asan activation/hibernation MAC CE.

The second MAC CE may have the fixed size of 1 byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1621 of FIG. 16B. The MAC CE 1621 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1623 of FIG. 16B. The MAC CE 1623 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates statetransition to the dormant state if the state for the SCell configuredwith SCellIndex i is the activated state, indicates the state transitionto the activated state if the state for the SCell is the dormant state,and indicates the transition state to the deactivated state if the statefor the SCell is the deactivated state. However, when the C(i) fieldconfigured with SCellIndex i is configured as one value (0 or 1, forexample, 0) of 1-bit information, the C(i) field may indicate to notperform state transition for the SCell or the one value (for example, 0)may be a reserved value.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the fifth embodiment maybe defined as shown in Table 14 below.

TABLE 14 C(i) field State transition 0 No state transition or reserved 1Ac→Do, Do→Ac, De→De

Not only first MAC control information and second MAC controlinformation, but also third MAC control information is defined. ThirdMAC control information, that is, the third MAC CE in the fifthembodiment is described below. The third MAC CE may be referred to as adeactivation/hibernation MAC CE.

The third MAC CE may have the fixed size of 1 byte and may be identifiedby an LCID. The third MAC CE may have seven C fields and one R field anda detailed format thereof is the same as that of an MAC CE 1631 of FIG.16B. The MAC CE 1631 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1633 of FIG. 16B. The MAC CE 1633 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thethird MAC CE having the size of 1 byte may be used. Otherwise, the thirdMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates statetransition to the dormant state if the state for the SCell configuredwith SCellIndex i is deactivated state, indicates the state transitionto the deactivated state if the state for the SCell is the dormantstate, and indicates the transition state to the activated state if thestate for the SCell is the activated state. However, when the C(i) fieldconfigured with SCellIndex i is configured as one value (0 or 1, forexample, 0) of 1-bit information, the C(i) field may indicate to notperform state transition for the SCell or the one value (for example, 0)may be a reserved value.

R field: denotes a reserved field and is configured as 0.

The third MAC control information according to the fifth embodiment maybe defined as shown in Table 15 below.

TABLE 15 C(i) field State transition 0 No state transition or reserved 1Ac→Ac, Do→De, De→Do

In the first MAC CE, the second MAC CE, and the third MAC CE accordingto the fifth embodiment, MAC CEs having the size of 1 byte and MAC CEshaving the size of 4 bytes may be distinguished through different LCIDs.Each of the first MAC CE, the second MAC CE, and the third MAC CE mayhave a fixed length. Accordingly, in this case, an L field is not neededin a MAC sub header.

The MAC control information indicating the state transition in thedisclosure should support all state transitions for each SCell of FIG.11. When the first MAC CE, the second MAC CE, and the third MAC CE inthe fifth embodiment of the disclosure are used, it may be easilyidentified whether all state transitions of FIG. 11 are supported. Itmay be intuitively identified whether the fifth embodiment supports allstate transitions for each SCell of FIG. 11 based on the description andtables of FIG. 16A.

FIGS. 17A and 17B are illustrations of a sixth embodiment of MAC controlinformation supporting state transition for an SCell in a wirelesscommunication system according to an embodiment. The sixth embodiment ofthe MAC control information is described below with reference to FIG.11. The sixth embodiment of the MAC control information supports thestate transition 1130 (De to Do) of FIG. 11. That is, even though thefrequency or the usage of use cases of the state transition 1130 (De toDo) is low, it is possible to save battery power of the UE and report afrequency measurement result in advance by switching the SCell in thedeactivated state to the dormant state. The eNB may determine whether toperform activation according to the reported frequency measurementresult and, thus, the state transition 1130 may be used.

Referring to FIGS. 17A and 17B, a first MAC CE, a second MAC CE, and athird MAC CE are defined as the MAC control information, and statetransition according to the first MAC CE, the second MAC CE, or thethird MAC CE is supported. The first MAC CE does not perform statetransition for the dormant state of the SCell. The second MAC CEcontinuously maintains the deactivated state for the SCell which is inthe deactivated state through one value (0 or 1, for example, 1) of1-bit information. Further, the second MAC CE does not perform statetransition for the SCell through one value (0 or 1, for example, 0) of1-bit information. The third MAC CE continuously maintains the activatedstate for the SCell which is in the activated state through one value (0or 1, for example, 1) of 1-bit information. Further, the third MAC CEdoes not perform state transition for the SCell through one value (0 or1, for example, 0) of 1-bit information.

First MAC control information, that is, the first MAC C in the sixthembodiment is described below. The first MAC CE may be referred to as anactivation/deactivation MAC CE. The first MAC CE may have the fixed sizeof 1 byte and may be identified by an LCID. The first MAC CE may haveseven C fields and one R field and a detailed format thereof is the sameas that of an MAC CE 1711 of FIG. 17B. The MAC CE 1711 consists of oneoctet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31.0 fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1713 of FIG. 17B. The MAC CE 1713 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the deactivated state, or the dormant state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to 1, the C(i)field indicates that the state of the SCell configured with SCellIndex ishould be activated. When the C(i) field is set to 0, the C(i) fieldindicates that the state of the SCell configured with SCellIndex i isdeactivated. However, when the state of the SCell configured withSCellIndex i is the dormant state, the MAC entity ignores the C(i)field.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the sixth embodiment may be defined asshown in Table 16 below.

TABLE 16 C(i) field State transition 0 Ac→De, Do→Do, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in the sixthembodiment is described below. The second MAC CE may be referred to as ahibernation MAC CE.

The second MAC CE may have the fixed size of 1 byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1721 of FIG. 17B. The MAC CE 1721 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1723 of FIG. 17B. The MAC CE 1723 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates statetransition to the dormant state if the state for the SCell configuredwith SCellIndex i is the activated state, indicates the state transitionto the deactivated state if the state for the SCell is the dormantstate, and indicates the transition state to the deactivated state ifthe state for the SCell is the deactivated state. However, when the C(i)field configured with SCellIndex i is configured as one value (0 or 1,for example, 0) of 1-bit information, the C(i) field may indicate to notperform state transition for the SCell or the one value (for example, 0)may be a reserved value.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the sixth embodiment maybe defined as shown in Table 17 below.

TABLE 17 C(i) field State transition 0 No state transition or reserved 1Ac→Do, Do→De, De→De

Third MAC control information, that is, the third MAC CE in the sixthembodiment is described below. The third MAC CE may be referred to as anactivation MAC CE.

The third MAC CE may have the fixed size of 1 byte and may be identifiedby an LCID. The third MAC CE may have seven C fields and one R field anda detailed format thereof is the same as that of an MAC CE 1731 of FIG.17B. The MAC CE 1731 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1733 of FIG. 17B. The MAC CE 1733 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thethird MAC CE having the size of 1 byte may be used. Otherwise, the thirdMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates statetransition to the dormant state if the state for the SCell configuredwith SCellIndex i is deactivated state, indicates the state transitionto the activated state if the state for the SCell is the dormant state,and indicates the transition state to the activated state if the statefor the SCell is the activated state. However, when the C(i) fieldconfigured with SCellIndex i is configured as one value (0 or 1, forexample, 0) of 1-bit information, the C(i) field may indicate to notperform state transition for the SCell or the one value (for example, 0)may be a reserved value.

R field: denotes a reserved field and is configured as 0.

The third MAC control information according to the sixth embodiment maybe defined as shown in Table 18 below.

TABLE 18 C(i) field State transition 0 No state transition or reserved 1Ac→Ac, Do→Ac, De→Do

In the first MAC CE, the second MAC CE, and the third MAC CE accordingto the sixth embodiment, MAC CEs having the size of 1 byte and MAC CEshaving the size of 4 bytes may be distinguished through differentlogical channel identifiers. Each of the first MAC CE, the second MACCE, and the third MAC CE may have a fixed length. Accordingly, in thiscase, an L field is not needed in a MAC sub header.

The MAC control information indicating the state transition in thedisclosure should support all state transitions for each SCell of FIG.11. When the first MAC CE, the second MAC CE, and the third MAC CE inthe sixth embodiment of the disclosure are used, it may be easilyidentified whether all state transitions of FIG. 11 are supported. Itmay be intuitively identified whether the sixth embodiment supports allstate transitions for each SCell of FIG. 11 based on the description andtables of FIG. 17A.

FIGS. 18A and 18B illustrate a seventh embodiment of MAC controlinformation supporting state transition for an SCell in a wirelesscommunication system according to an embodiment. The seventh embodimentof the MAC control information is described with reference to FIG. 11.The seventh embodiment of the MAC control information supports the statetransition 1130 (De to Do) of FIG. 11. That is, even though thefrequency or the usage of use cases of the state transition 1130 (De toDo) is low, it is possible to save battery power of the UE and report afrequency measurement result in advance by switching the SCell in thedeactivated state to the dormant state. The eNB may determine whether toperform activation according to the reported frequency measurementresult and thus the state transition 1130 may be useful.

Referring to FIGS. 18A and 18B, a first MAC CE, a second MAC CE, and athird MAC CE are defined as the MAC control information, and statetransition according to the first MAC CE, the second MAC CE, or thethird MAC CE is supported. The first MAC CE does not perform statetransition for the dormant state of the SCell. The second MAC CE doesnot perform state transition for the deactivated state of the SCell. Thethird MAC CE does not perform state transition for the activated stateof the SCell.

First MAC control information, that is, the first MAC C in the seventhembodiment is described below. The first MAC CE may be referred to as anactivation/deactivation MAC CE. The first MAC CE may have the fixed sizeof 1 byte and may be identified by an LCID. The first MAC CE may haveseven C fields and one R field and a detailed format thereof is the sameas that of an MAC CE 1811 of FIG. 18B. The MAC CE 1811 consists of oneoctet.

Further, the first MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The first MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1813 of FIG. 18B. The MAC CE 1813 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thefirst MAC CE having the size of 1 byte may be used. Otherwise, the firstMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the deactivated state, or the dormant state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to 1, the C(i)field indicates that the state of the SCell configured with SCellIndex ishould be activated. When the C(i) field is set to 0, the C(i) fieldindicates that the state of the SCell configured with SCellIndex i isdeactivated. However, when the state of the SCell configured withSCellIndex i is the dormant state, the MAC entity ignores the C(i)field.

R field: denotes a reserved field and is configured as 0.

The first MAC CE according to the seventh embodiment may be defined asshown in Table 19 below.

TABLE 19 C(i) field State transition 0 Ac→De, Do→Do, De→De 1 Ac→Ac,Do→Do, De→Ac

Second MAC control information, that is, the second MAC CE in theseventh embodiment is described below. The second MAC CE may be referredto as an activation/hibernation MAC CE.

The second MAC CE may have the fixed size of 1 byte and may beidentified by an LCID. The second MAC CE may have seven C fields and oneR field and a detailed format thereof is the same as that of an MAC CE1821 of FIG. 18B. The MAC CE 1821 consists of one octet.

Further, the second MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The second MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1823 of FIG. 18B. The MAC CE 1823 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thesecond MAC CE having the size of 1 byte may be used. Otherwise, thesecond MAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MACentity ignores this field. When the C(i) field is set to one value (0 or1, for example, 1) of 1-bit information, the C(i) field indicates statetransition to the activated state if the state for the SCell configuredwith SCellIndex i is the activated state, indicates the state transitionto the activated state if the state for the SCell is the dormant state,and indicates the transition state to the deactivated state if the statefor the SCell is the deactivated state. When the C(i) field is set toone value (0 or 1, for example, 0) of 1-bit information, the C(i) fieldindicates state transition to the dormant state if the state for the SCell configured with SCellIndex i is the activated state, indicates thestate transition to the dormant state if the state for the SCell is thedormant state, and indicates the transition state to the deactivatedstate if the state for the SCell is the deactivated state.

R field: denotes a reserved field and is configured as 0.

The second MAC control information according to the seventh embodimentmay be defined as shown in Table 20 below.

TABLE 20 C(i) field State transition 0 Ac→Do, Do→Do, De→De 1 Ac→Ac,Do→Ac, De→De

Third MAC control information, that is, the third MAC CE in the seventhembodiment is described below. The third MAC CE may be referred to as adeactivation/hibernation MAC CE.

The third MAC CE may have the fixed size of 1 byte and may be identifiedby an LCID. The third MAC CE may have seven C fields and one R field anda detailed format thereof is the same as that of an MAC CE 1831 of FIG.18B. The MAC CE 1831 consists of one octet.

Further, the third MAC CE may have the fixed size of 4 bytes and may beidentified by an LCID. The third MAC CE may have 31 C fields and one Rfield and a detailed format thereof is the same as that of an MAC CE1833 of FIG. 18B. The MAC CE 1833 consists of 4 octets.

If configured cell identifiers (SCell indexes) do not exceed 7, thethird MAC CE having the size of 1 byte may be used. Otherwise, the thirdMAC CE having the size of 4 bytes may be used.

C(i) field: indicates that the SCell configured with SCellIndex i is inthe activated state, the dormant state, or the deactivated state ifthere is an SCell configured with SCellIndex i. Otherwise, the MAC rignores this field. When the C(i) field is set to one value (0 or 1, forexample, 1) of 1-bit information, the C(i) field indicates statetransition to the activated state if the state for the SCell configuredwith SCellIndex i is the activated state, indicates the state transitionto the activated state if the state for the SCell is the dormant state,and indicates the transition state to dormant state if the state for theSCell is the deactivated state. When the C(i) field is set to one value(0 or 1, for example, 0) of 1-bit information, the C(i) field indicatesstate transition to the activated state if the state for the SCellconfigured with SCellIndex i is the activated state, indicates the statetransition to the deactivated state if the state for the SCell is thedormant state, and indicates the transition state to the deactivatedstate if the state for the SCell is the deactivated state.

R field: denotes a reserved field and is configured as 0.

The third MAC control information according to the seventh embodimentmay be defined as shown in Table 21 below.

TABLE 21 C(i) field State transition 0 Do→De, De→De, Ac→Ac 1 De→Do,Ac→Ac, Do→Do

In the first MAC CE, the second MAC CE, and the third MAC CE accordingto the seventh embodiment, MAC CEs having the size of 1 byte and MAC CEshaving the size of 4 bytes may be distinguished through differentlogical channel identifiers. Each of the first MAC CE, the second MACCE, and the third MAC CE may have a fixed length. Accordingly, in thiscase, an L field is not needed in a MAC sub header.

The MAC control information indicating the state transition in thedisclosure should support all state transitions for each SCell of FIG.11. When the first MAC CE, the second MAC CE, and the third MAC CE inthe seventh embodiment of the disclosure are used, it may be easilyidentified whether all state transitions of FIG. 11 are supported. Itmay be intuitively identified whether the sixth embodiment supports allstate transitions for each SCell of FIG. 11 based on the description andtables of FIG. 17A.

According to an embodiment, the eNB transmits frequency measurementconfiguration information to the UE. The UE is configured based onfrequency measurement configuration information. In the disclosure, theeNB may configure RRC connection reconfiguration (for example, CAconfiguration, CSI configuration, or sounding reference signal (SRS)configuration) in the UE through the RRC message (for example, RRCconnection setup or RRC connection reconfiguration). CSI, SRS, bandwidthpart (BWP) configuration may include periodic CSI (P-CSI),semi-persistent CSI (SP-CSI), or aperiodic CSI (AP-CSI) configurationfor each special cell (SpCell)/upload (UL) BWP or P-SRS configurationfor each serving cell/UL BWP. The SpCell may be a Pcell of each cellgroup in DC, that is, a Pcell of a master cell group (MCG) and a PSCellof a secondary cell group (SCG). CA configuration may include DL BWP orUL BWP configuration for each SCell, SCell index (SCellIndex)configuration, or initially configured state (activated state,deactivated state, or dormant state).

Hereinafter, operations of the UE according to the initial state of theSCell are described.

In serving cells of which the initial state is the activated state, theUE may perform operation 1 after operation 1-1. In serving cells ofwhich the initial state is the deactivated state, the UE may performoperation 3. A time point at which operation 1-1 is applied may be asubframe n+x. A subframe n may be a subframe in which an RRC message forconfiguring the initial state as the activated state is received, and xmay be a predetermined integer or an integer configured through an RRCmessage. Operation 1-1 includes at least one of power headroom (PHR)trigger and SCellDeactivationTimer start. Operation 1 includes at leastone of PDCCH monitoring, CSI report, SRS transmission,SCellDeactivationTimer driving, type 1 CG transmission, serving cellmeasurement in every DRX cycle. Operation 3 includes serving cellmeasurement in every greater value among the DRX cycle andsCellMeasCycle, that is, every Max [DRX cycle, sCellMeasCycle]. ThesCellMeasCycle is a parameter for determining an SCell measurementinterval.

For serving cells (SCells) receiving a MAC CE indicating statetransition of the serving cell and instructed to be in the activatedstate according to various embodiments of the disclosure, the UE mayperform operation 1 after operation 1-1. A time point at which operation1-1 is applied may be a subframe m+y, and the subframe m may be asubframe receiving the MAC CE and y is a predetermined integer or aninteger configured through an RRC message. For serving cells (SCells)receiving the MAC CE in the disclosure and instructed to be in thedeactivated state, the UE starts operation 3 after operation 3-1 insubframe m+z. z may be a predetermined integer or an integer configuredthrough an RRC message. For serving cells of which the initial state isconfigured as the dormant state or serving cells receiving the MAC CEand transitioning to the dormant state, the UE may continuously performoperation 2. Operation 3-1 may include at least one of an operation forstopping or resetting a timer for the SCell (SCellDeactivationTimer),deactivate type 2 configured grant (CG), and suspend type 2 CG.Operation 2 may include at least one of CSI report, SRS transmission,serving cell measurement in every DRX cycle, and measurement resultreport.

In dormant state serving cells receiving the MAC CE and instructed totransition to the activated state according to various embodiments ofthe disclosure indicating state transition of the serving cell, the UEperforms operation 1 after operation 1-1. In activated state servingcells receiving the MAC CE and instructed to transition to the dormantstate, the UE performs operation 2 after operation 2-1. A time point atwhich operation 1-1 and operation 2-1 are applied may be a symbol k+y(for example, a symbol in which the UE completes HARQ feedbacktransmission for the received MAC CE). Operation 2-1 may include atleast one of an operation for stopping or resetting a timer for theSCell (SCellDeactivationTimer), deactivate type 2 CG, and suspend type 2CG. The symbol k may be a symbol in which the MAC CE is received, and ymay be a predetermined integer or an integer configured through an RRCmessage.

FIG. 19 is a block diagram of an eNB 1900 in a wireless communicationsystem according to an embodiment. The eNB 1900 may be the eNB 110 ofFIG. 1, the gNB 310, or the eNB 315 of FIG. 3. The term “ . . . unit” orthe ending of a word, such as “ . . . or”, “ . . . er”, or the like mayindicate a unit of processing at least one function or operation, andthis may be embodied by hardware, software, or a combination of hardwareand software.

Referring to FIG. 19, the eNB 1900 includes a wireless communicationunit 1910, a backhaul communication unit 1920, a storage unit 1930, anda controller 1940.

The wireless communication unit 1910 performs functions for transmittingand receiving signals through a wireless channel. For example, thecommunication unit 1910 performs a function of conversion between abaseband signal and a bit stream according to a physical layer standardof the system. For example, in data transmission, the wirelesscommunication unit 1910 generates complex symbols by encoding andmodulating a transmission bitstream. In data reception, thecommunication unit 1910 restores a reception bitstream by demodulatingand decoding a baseband signal. The wireless communication unit 1910up-converts a baseband signal into a radio frequency (RF) band signaland transmits the same through an antenna, and down-converts an RF bandsignal received through an antenna into a baseband signal.

To this end, the wireless communication unit 1910 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a digital-to-analog convertor (DAC), an analog-to-digitalconvertor (ADC), and the like. Further, the wireless communication unit1910 may include a plurality of transmission/reception paths. Inaddition, the wireless communication unit 1910 may include at least oneantenna array consisting of a plurality of antenna elements. On thehardware side, the wireless communication unit 1910 may include adigital unit and an analog unit, and the analog unit may include aplurality of sub-units according to operation power, operationfrequency, and the like.

The wireless communication unit 1910 may transmit and receive a signal.For example, the wireless communication unit 1910 may transmit asynchronization signal, a reference signal, system information, amessage, control information, or data. The wireless communication unit1910 may perform beamforming. The wireless communication unit 1910 mayapply a beamforming weighted value to a signal in order to assigndirectivity according to settings of the controller 1940 to the signalto be transmitted and received.

The wireless communication unit 1910 transmits and receives the signalas described above. Accordingly, some or all of the wirelesscommunication unit 1910 may be referred to as a “transmitter”, a“receiver”, or a “transceiver”. In addition, the transmission andreception performed through a wireless channel, which is described inthe following descriptions, may be understood to indicate that theabove-described processing is performed by the communication unit 1910.

The backhaul communication unit 1920 provides an interface forperforming communication with other nodes within the network. That is,the backhaul communication unit 1920 converts a bit stream transmittedfrom the base station to another node, for example, another access node,another base station, or a core network, into a physical signal, andconverts a physical signal received from another node into a bit stream.

The storage unit 1930 stores data, such as a basic program for operatinga base station, an application, configuration information, and the like.For example, the storage unit 1930 may store information on a bearerallocated to the accessed UE and a measurement result reported from theaccessed UE. For example, the storage unit 1930 may store informationwhich is a reference for determining whether to provide or stop multipleconnections to the UE. The storage unit 1930 may be configured asvolatile memory, non-volatile memory, or a combination of volatilememory and non-volatile memory. Further, the storage unit 1930 providesstored data in response to a request from the controller 1940.

The controller 1940 controls the overall operation of the eNB 1900. Forexample, the controller 1940 transmits and receives a signal through thewireless communication unit 1910 or the backhaul communication unit1920. Further, the controller 1940 records data in the storage unit 1930and reads the recorded data. The controller 1940 may perform thefunctions of a protocol stack (for example, illustrated in FIG. 2 or 4)required by communication standards. To this end, the controller 1940may include at least one processor. According to an embodiment, thecontroller 1940 may control the eNB 1900 to perform operations accordingto various embodiments described below.

FIG. 20 illustrates an example of the configuration of a UE 2000 in awireless communication system according to an embodiment of thedisclosure. The UE 2000 may be understood as the configuration of the UE135 of FIG. 1 or the UE 315 of FIG. 3. The term “ . . . unit” or theending of a word, such as “ . . . or”, “ . . . er”, or the like mayindicate a unit of processing at least one function or operation, andthis may be embodied by hardware, software, or a combination of hardwareand software. Referring to FIG. 20, the UE 2000 includes a communicationunit 2010, a storage unit 2020, and a controller 2030.

The communication unit 2010 performs functions fortransmitting/receiving a signal through a wireless channel. For example,the communication unit 2010 performs a function of conversion between abaseband signal and a bit stream according to a physical layer standardof the system. For example, in data transmission, the communication unit2010 generates complex symbols by encoding and modulating a transmissionbitstream. In data reception, the communication unit 2010 restores areception bit stream by demodulating and decoding a baseband signal. Inaddition, the communication unit 2010 up-converts a baseband signal intoa RF band signal and transmits the same through an antenna, anddown-converts an RF band signal received through an antenna into abaseband signal. For example, the communication unit 2010 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a DAC, an ADC, and the like.

Further, the communication unit 2010 may include a plurality oftransmission/reception paths. In addition, the communication unit 2010may include an antenna unit. The communication unit 2010 may include atleast one antenna array consisting of a plurality of antenna elements.On the hardware side, the communication unit 2010 may include a digitalcircuit and an analog circuit (for example, an RFIC). The digitalcircuit and the analog circuit may be implemented as one package. Thecommunication unit 2010 may include a plurality of RF chains. Thecommunication unit 2010 may perform beamforming. The communication unit2010 may apply a beamforming weighted value to a signal in order toassign directivity according to settings of the controller 2030 to thesignal to be transmitted and received.

The communication unit 2010 may transmit and receive a signal. Thecommunication unit 2010 may receive a downlink signal. The downlinksignal may include a synchronization signal (SS), a reference signal(RS) (for example, a CRS, a demodulation (DM)-RS), system information(for example, a master information block (MIB), an SIB, remaining system(RMSI), and other system information (OSI)), a configuration message,control information, or downlink data. The communication unit 2010 maytransmit an uplink signal. The uplink signal may include a randomaccess-related signal (for example, a RAP (or Message 1 (Msg1), Message3 (Msg3)), or a reference signal (for example, an SRS or a DM-RS). Thecommunication unit 2010 may include different communication modules toprocess signals in different frequency bands. In addition, thecommunication unit 2010 may include a plurality of communication modulesfor supporting a plurality of different radio access technologies. Forexample, the different radio access technologies may include Bluetoothlow energy (BLE), wireless fidelity (Wi-Fi), Wi-Fi gigabyte (WiGig), andcellular network (for example, LTE, new radio (NR)). Further, differentfrequency bands may include a super high frequency (SHF) (for example,2.5 GHz and 5 GHz) band and a millimeter (mm) wave (for example, 38 GHzand 60 GHz) band. The communication unit 2010 may use the same type ofRAT in an unlicensed band for different frequency bands (for example,licensed assisted access (LAA)) and citizens broadband radio service(CBRS) (for example, 3.5 GHz).

The communication unit 2010 transmits and receives the signal asdescribed above. Accordingly, all or some of the communication units2010 may be referred to as a transmitter, a receiver, or a transceiver.In addition, the transmission and reception performed through a wirelesschannel, which is described in the following descriptions, may beunderstood to indicate that the above-described processing is performedby the communication unit 2010.

The storage unit 2020 may store data, such as a basic program foroperating a terminal, an application, configuration information, and thelike. The storage unit 2020 may be configured as volatile memory,non-volatile memory, or a combination of volatile memory andnon-volatile memory. Further, the storage unit 2020 provides stored datain response to a request from the controller 2030.

The controller 2030 controls the overall operation of the UE 2000. Thecontroller 2030 may include at least one processor. For example, thecontroller 330 may include a communication processor (CP) that performsa control for communication, and an application processor (AP) thatcontrols a higher layer such as an application. For example, thecontroller 2030 transmits and receives a signal through thecommunication unit 2010. Further, the controller 2030 records data inthe storage unit 2020 and reads the data. The controller 2030 mayperform functions of a protocol stack (for example, illustrated in FIG.2 or 4) required by the communication standard. To this end, thecontroller 2030 may include at least one processor or microprocessor, ormay play the part of the processor. A portion of the communication unit2010 and the controller 2030 may be referred to as a CP. The controller2030 may include various modules for performing communication.

Each function and operation within the controller 2030 are a set ofinstructions or code stored in the storage unit 2020, and may correspondto an instruction/code at least temporarily residing in the controller2030 or a storage space storing the instruction/code, a portion of thecircuitry included in the controller 2030, or a module for performingthe function of the controller 2030. According to various embodiments,the controller 2030 may control the UE 2000 to perform operationsaccording to various embodiments described below.

The configuration illustrated in FIG. 20 is only an example of the UE2000, and the UE 2000 is not limited thereto. That is, according tovarious embodiments, some elements may be added, deleted, or changed.

In the disclosure, although the terms “greater than or equal to” and“less than or equal to” are used to determine whether a particularcondition is fulfilled, this is only an example but does not exclude theterms “larger than (or larger than or equal to)” or “smaller than (orequal to or smaller than)”. For example, the condition “greater than orequal to” may be replaced with the condition “larger than”, thecondition “less than or equal to” may be replaced with the condition“smaller than”, the condition “larger than” may be replaced with thecondition “larger than or equal to”, the condition “smaller than” may bereplaced with the condition “equal to or smaller than”, the condition“larger than or equal to and smaller than” may be replaced with “largerthan and equal to or smaller than”, and the condition “larger than andequal to or smaller than” may be replaced with the condition “largerthan or equal to and smaller than”.

Methods according to embodiments stated in claims and/or the disclosuremay be implemented in hardware, software, or a combination of hardwareand software.

When the methods are implemented by software, a non-transitorycomputer-readable storage medium for storing one or more programs(software modules) may be provided. The one or more programs stored inthe non-transitory computer-readable storage medium may be configuredfor execution by one or more processors within the electronic device.The at least one program may include instructions that cause theelectronic device to perform the methods according to variousembodiments of the disclosure as defined by the appended claims and/ordisclosed herein.

The programs (software modules or software) may be stored innon-volatile memories including a random access memory and a flashmemory, a read only memory (ROM), an electrically erasable programmableROM (EEPROM), a magnetic disc storage device, a compact disc ROM(CD-ROM), a digital versatile disc (DVD), or other type optical storagedevices, or a magnetic cassette. Alternatively, any combination of someor all of the may form a memory in which the program is stored. Further,a plurality of such memories may be included in the electronic device.

In addition, the programs may be stored in an attachable storage devicewhich is accessible through communication networks such as the Internet,Intranet, a local area network (LAN), a wide area network (WAN), astorage area network (SAN), and a combination thereof. Such a storagedevice may access the electronic device via an external port. Further, aseparate storage device on the communication network may access aportable electronic device.

In the above-described detailed embodiments of the disclosure, acomponent included in the disclosure is expressed in the singular or theplural according to a presented detailed embodiment. However, thesingular form or plural form is selected for convenience of descriptionsuitable for the presented situation, and various embodiments of thedisclosure are not limited to a single element or multiple elementsthereof. Further, either multiple elements expressed in the descriptionmay be configured into a single element or a single element in thedescription may be configured into multiple elements.

While the disclosure has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the scope of the disclosure. Therefore, the scopeof the disclosure should not be defined as being limited to theembodiments, but is defined by the appended claims and equivalentsthereof.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising: identifying a first statusfor a secondary cell (SCell) of the terminal; identifying whether afirst medium access control (MAC) control element (CE) or a second MACCE is received from a base station, wherein the first MAC CE indicatesthat a status for the SCell is an activated state or a deactivatedstate, and the second MAC CE indicates that the status for the SCell isthe activated state or a dormant state; and determining a second statusfor the SCell based on the first MAC CE, in case that the first MAC CEis received from the base station and the second MAC CE is not receivedfrom the base station, wherein, in case that the first status for theSCell is the dormant state and the first MAC CE indicates that thestatus for the SCell is the activated state, the second status for theSCell is determined to be maintained as the dormant state.
 2. The methodof claim 1, further comprising: in case that the second status for theSCell is determined as the dormant state, performing at least one of areporting of a channel quality indicator (CQI), a radio resourcemanagement (RRM) measurement, or no monitoring for a physical downlinkcontrol channel (PDCCH) associated with the SCell.
 3. The method ofclaim 1, further comprising: identifying two bits for the SCell based onthe first MAC CE and the second MAC CE; and identifying the status forthe SCell as one of four states based on the two bits, wherein the fourstates include: a reserved, the activated state, the dormant state, anda deactivated state.
 4. The method of claim 1, further comprising: incase that a first timer expires and the status for the SCell is theactivated state, performing a first transition of the status for theSCell by hibernating the SCell from the activated state to the dormantstate; and when a second timer expires, performing a second transitionof the status for the SCell by deactivating the SCell from the dormantstate to a deactivated state.
 5. The method of claim 4, furthercomprising: receiving, from the base station, configuration informationfor the SCell by using a radio resource control (RRC) signaling, theconfiguration information including: a value of the first timer definedfor the first transition from the activated state to the dormant state;and a value of the second timer defined for the second transition fromthe dormant state to the deactivated state.
 6. The method of claim 2,wherein the CQI is reported periodically.
 7. The method of claim 1,further comprising: receiving, from the base station, configurationinformation for the SCell by using a radio resource control (RRC)signaling, the configuration information including information forindicating a status for the SCell; determining the status for the SCellbased on the information; wherein the determined status for the SCell isone of the activated state, the dormant state, and a deactivated state,and wherein receiving the second MAC CE comprises: identifying thesecond MAC CE based on a logical channel identifier (LCID) indicating ahibernation.
 8. The method of claim 1, further comprising: determiningthe second status for the SCell based on the first MAC CE and the secondMAC CE, in case that the first MAC CE and the second MAC CE are receivedfrom the base station, wherein the second status for the SCell isdetermined as the dormant state, in case that the first MAC CE indicatesthat the status for the SCell is the activated state, and the second MACCE indicates that the status for the SCell is the dormant state.
 9. Themethod of claim 1, wherein, in case that the first status for the SCellis the dormant state and the first MAC CE indicates that the status forthe SCell is the deactivated state, the second status for the SCell isdetermined as the deactivated state.
 10. The method of claim 1, wherein,in case that the first status for the SCell is the activated state orthe deactivated state, the second status for the SCell is determined asthe activated state or the deactivated state indicated by the first MACCE.
 11. A terminal in a wireless communication system, the terminalcomprising: a transceiver; and a processor configured to: identify afirst status for a secondary cell (SCell) of the terminal; identifywhether a first medium access control (MAC) control element (CE) or asecond MAC CE is received from a base station, wherein the first MAC CEindicates a status for the SCell is an activated state or a deactivatedstate, and the second MAC CE indicates that the status for the SCell isthe activated state or a dormant state; and determine a second statusfor the SCell based on the first MAC CE, in case that the first MAC CEis received from the base station and the second MAC CE is not receivedfrom the base station, wherein, in case that the first status for theSCell is the dormant state and the first MAC CE indicates that thestatus for the SCell is the activated state, the second status for theSCell is determined to be maintained as the dormant state.
 12. Theterminal of claim 11, wherein the processor is further configured to: incase that the second status for the SCell is determined as the dormantstate, perform at least one of a reporting of a channel qualityindicator (CQI), a radio resource management (RRM) measurement, or nomonitoring for a physical downlink control channel (PDCCH) associatedwith the SCell.
 13. The terminal of claim 11, wherein the processor isfurther configured to: identify two bits for the SCell based on thefirst MAC CE and the second MAC CE; and identify the status for theSCell as one of four states based on the two bits, wherein the fourstates include: a reserved, the activated state, the dormant state, anda deactivated state.
 14. The terminal of claim 11, wherein the processoris further configured to: in case that a first timer expires and thestatus for the SCell is the activated state, perform a first transitionof the status for the SCell by hibernating the SCell from the activatedstate to the dormant state; and when a second timer expires, perform asecond transition of the state of the SCell by deactivating the SCellfrom the dormant state to the deactivated state.
 15. The terminal ofclaim 14, wherein the processor is further configured to: receive, fromthe base station, configuration information for the SCell by using aradio resource control (RRC) signaling, the configuration informationincluding: a value of the first timer defined for the first transitionfrom the activated state to the dormant state; and a value of the secondtimer defined for the second transition from the dormant state to thedeactivated state.
 16. The terminal of claim 12, wherein the CQI isreported periodically.
 17. The terminal of claim 11, wherein theprocessor is further configured to: receive, from the base station,configuration information for the SCell by using a radio resourcecontrol (RRC) signaling, the configuration information includinginformation for indicating a status for the SCell; determine the statusfor the SCell based on the information; wherein the determined statusfor the SCell is one of the activated state, the dormant state, and adeactivated state, and wherein receiving the second MAC CE comprises:identifying the second MAC CE based on a logical channel identifier(LCID) indicating a hibernation.
 18. The terminal of claim 11, whereinthe processor is further configured to: determine the second status forthe SCell based on the first MAC CE and the second MAC CE, in case thatthe first MAC CE and the second MAC CE are received from the basestation, wherein the second status for the SCell is determined as thedormant state, in case that the first MAC CE indicates that the statusfor the SCell is the activated state, and the second MAC CE indicatesthat the status for the SCell is the dormant state.
 19. The terminal ofclaim 11, wherein, in case that the first status for the SCell is thedormant state and the first MAC CE indicates that the status for theSCell is the deactivated state, the second status for the SCell isdetermined as the deactivated state.
 20. The terminal of claim 11,wherein, in case that the first status for the SCell is the activatedstate or the deactivated state, the second status for the SCell isdetermined as the activated state or the deactivated state indicated bythe first MAC CE.
 21. A base station in a wireless communication system,the base station comprising: a transceiver; and a processor configuredto: transmit, to a terminal via the transceiver, a first medium accesscontrol (MAC) control element (CE) or a second MAC CE, wherein the firstMAC CE indicates that a status for a secondary cell (SCell) is anactivated state or a deactivated state, and the second MAC CE indicatesthat the status for the SCell is the activated state or a dormant state,wherein the SCell is in a first status before the base station transmitsthe first MAC CE or the second MAC CE, wherein a second status for theSCell is determined based on the first MAC CE, in case that the firstMAC CE is transmitted to the terminal and the second MAC CE is nottransmitted to the terminal, wherein, in case that the first status forthe SCell is the dormant state and the first MAC CE indicates that thestatus for the SCell is the activated state, the second status for theSCell is determined to be maintained as the dormant state, wherein, incase that the status for the SCell before the determination is theactivated state or the deactivated state and the first MAC CEtransmitted to the terminal indicates the status for the SCell as theactivated state and the second MAC CE is not transmitted to theterminal, the status for the SCell is determined as the activated state.22. The base station of claim 21, wherein, in case that the secondstatus for the SCell is determined as the dormant state, at least one ofa reporting of a channel quality indicator (CQI), a radio resourcemanagement (RRM) measurement, or no monitoring for a physical downlinkcontrol channel (PDCCH) associated with the SCell is performed.
 23. Thebase station of claim 21, wherein two bits for the SCell are identifiedbased on the first MAC CE and the second MAC CE, wherein the two bitsindicate the status for the SCell as one of four states, and wherein thefour states include: a reserved, the activated state, the dormant state,and a deactivated state.
 24. The base station of claim 21, wherein theprocessor is further configured to: transmit, to the terminal,configuration information for the SCell by using a radio resourcecontrol (RRC) signaling, the configuration information including: avalue of a first timer defined for a first transition from the activatedstate to the dormant state; and a value of a second timer defined for asecond transition from the dormant state to a deactivated state.
 25. Thebase station of claim 22, wherein the CQI is reported periodically. 26.The base station of claim 21, wherein the processor is furtherconfigured to: transmit, to the terminal, configuration information forthe SCell by using a radio resource control (RRC) signaling, theconfiguration information including information for indicating a statusfor the SCell, wherein the status for the SCell is one of the activatedstate, the dormant state, and a deactivated state, and wherein thesecond MAC CE is identified based on a logical channel identifier (LCID)indicating a hibernation.
 27. The base station of claim 21, wherein thesecond status for the SCell is determined based on the first MAC CE andthe second MAC CE, in case that the first MAC CE and the second MAC CEare transmitted to the terminal, and wherein the status for the SCell isdetermined as the dormant state, in case that the first MAC CE indicatesthat the status for the SCell is the activated state, and the second MACCE indicates that the sttus for the SCell is the dormant state.
 28. Thebase station of claim 21, wherein, in case that the first status for theSCell is the dormant state and the first MAC CE indicates that thestatus for the SCell is the deactivated state, the second status for theSCell is determined as the deactivated state.
 29. The base station ofclaim 21, wherein, in case that the first status for the SCell is theactivated state or the deactivated state, the second status for theSCell is determined as the activated state or the deactivated stateindicated by the first MAC CE.
 30. A method performed by a base stationin a wireless communication system, the method comprising: transmitting,to a terminal, a first medium access control (MAC) control element (CE)or a second MAC CE, wherein the first MAC CE indicates a status for asecondary cell (SCell) as an activated state or a deactivated state, andthe second MAC CE indicates the status for the SCell as the activatedstate or a dormant state, wherein the SCell is in a first status beforethe base station transmits the first MAC CE or the second MAC CE,wherein a second status for the SCell is determined based on the firstMAC CE, in case that the first MAC CE is transmitted to the terminal andthe second MAC CE is not transmitted to the terminal, wherein, in casethat the first status for the SCell is the dormant state and the firstMAC CE indicates that the status for the SCell is the activated state,the second status for the SCell is determined to be maintained as thedormant state.
 31. The method of claim 30, wherein, in case that thesecond status for the SCell is determined as the dormant state, at leastone of a reporting of a channel quality indicator (CQI), a radioresource management (RRM) measurement, or no monitoring for a physicaldownlink control channel (PDCCH) associated with the SCell is performed.32. The method of claim 30, wherein two bits for the SCell areidentified based on the first MAC CE and the second MAC CE, wherein thetwo bits indicate the status for the SCell as one of four states, andwherein the four states include: a reserved, the activated state, thedormant state, and a deactivated state.
 33. The method of claim 30,further comprising: transmitting, to the terminal, configurationinformation for the SCell by using a radio resource control (RRC)signaling, the configuration information including: a value of a firsttimer defined for a first transition from the activated state to thedormant state; and a value of a second timer defined for a secondtransition from the dormant state to a deactivated state.
 34. The methodof claim 31, wherein the CQI is reported periodically.
 35. The method ofclaim 30, further comprising: transmitting, to the terminal,configuration information for the SCell by using a radio resourcecontrol (RRC) signaling, the configuration information includinginformation for indicating a status for the SCell, wherein the statusfor the SCell is one of the activated state, the dormant state, and adeactivated state, and wherein the second MAC CE is identified based ona logical channel identifier (LCD) indicating a hibernation.
 36. Themethod of claim 30, wherein the second status for the SCell isdetermined based on the first MAC CE and the second MAC CE, in case thatthe first MAC CE and the second MAC CE are transmitted to the terminal,and wherein the status for the SCell is determined as the dormant state,in case that the first MAC CE indicates that the status for the SCell isthe activated state, and the second MAC CE indicates that the status forthe SCell is the dormant state.
 37. The method of claim 30, wherein, incase that the first status for the SCell is the dormant state and thefirst MAC CE indicates that the status for the SCell is the deactivatedstate, the second status for the SCell is determined as the deactivatedstate.
 38. The method of claim 30, wherein, in case that the firststatus for the SCell is the activated state or the deactivated state,the second status for the SCell is determined as the activated state orthe deactivated state indicated by the first MAC CE.